On an 18-hole golf course, there are par-3 holes, par-4 holes, and par-5 holes. A golfer who shoots par on every hole has a total of 66. There are twice as many par-4 holes as there are par-5 holes. How many of each type of hole are there on the golf course?

How many par-3 holes are there__?
How many par-4 holes are there__?
How many par-5 holes are there__?

I'm not sure if I did this right, but I followed your formula, and got 9,6, and 3 as the answer. Is this correct?

let there b x par-3, y par-4, z par-5 holes. Then

x+y+z = 18
3x+4y+5z = 66
y = 2z

Now just solve for x,y,z

Let's use algebra to solve this problem. Let's represent the number of par-3 holes as x, the number of par-4 holes as y, and the number of par-5 holes as z.

We are given the following information:
1. The total score for shooting par on every hole is 66.
2. There are twice as many par-4 holes as par-5 holes.

Based on the first point, we can set up the following equation:
Par 3 score + Par 4 score + Par 5 score = 66

For a par-3 hole, the score is 3. So the Par 3 score would be 3x.
For a par-4 hole, the score is 4. So the Par 4 score would be 4y.
For a par-5 hole, the score is 5. So the Par 5 score would be 5z.

Now we can set up the equation based on the given information:
3x + 4y + 5z = 66 ---(1)

We also know from the second point that there are twice as many par-4 holes as par-5 holes:
y = 2z ---(2)

To solve these equations, we'll use the substitution method. We'll solve equation (2) for y in terms of z and substitute it into equation (1). Here's how:

From equation (2), we have: y = 2z

Substituting y = 2z in equation (1):
3x + 4(2z) + 5z = 66
3x + 8z + 5z = 66
3x + 13z = 66 ---(3)

Now, we need to find values of x, y, and z that satisfy equations (2) and (3).

Let's try different values for z and solve for x and y.

If we assume z = 1, then from equation (2), y = 2(1) = 2.

Substituting z = 1 in equation (3):
3x + 13(1) = 66
3x + 13 = 66
3x = 66 - 13
3x = 53
x = 53/3
x ≈ 17.67

But since the number of holes can only be whole numbers, this assumption doesn't work.

Let's try another value for z.

If we assume z = 2, then from equation (2), y = 2(2) = 4.

Substituting z = 2 in equation (3):
3x + 13(2) = 66
3x + 26 = 66
3x = 66 - 26
3x = 40
x = 40/3
x ≈ 13.33

Again, the number of holes cannot be a fraction. So, this assumption also doesn't work.

Let's try one more value for z.

If we assume z = 3, then from equation (2), y = 2(3) = 6.

Substituting z = 3 in equation (3):
3x + 13(3) = 66
3x + 39 = 66
3x = 66 - 39
3x = 27
x = 27/3
x = 9

Now we have a valid solution: x = 9, y = 6, z = 3.

Therefore, the number of par-3 holes is 9, the number of par-4 holes is 6, and the number of par-5 holes is 3.

To answer these questions, we can set up a system of equations based on the information given. Let's denote the number of par-3 holes as "x", the number of par-4 holes as "y", and the number of par-5 holes as "z".

We are told that there are twice as many par-4 holes as par-5 holes. Mathematically, this can be written as:

y = 2z (Equation 1)

The total score for a golfer who shoots par on every hole is 66. Each par-3 hole has a par score of 3, each par-4 hole has a par score of 4, and each par-5 hole has a par score of 5. Therefore, we can write the equation:

3x + 4y + 5z = 66 (Equation 2)

Now, we have a system of two equations with three variables. We can solve this system to find the values of x, y, and z.

First, let's substitute the value of y from Equation 1 into Equation 2:

3x + 4(2z) + 5z = 66

Simplifying:

3x + 8z + 5z = 66
3x + 13z = 66 (Equation 3)

We now have two equations involving x and z: Equation 1 and Equation 3. We can solve these equations simultaneously.

To make it easier, let's isolate x in Equation 3:

3x = 66 - 13z
x = (66 - 13z) / 3 (Equation 4)

Substitute the value of x from Equation 4 into Equation 1:

(66 - 13z) / 3 = 2z

Multiply both sides by 3 to eliminate the fraction:

66 - 13z = 6z

Combine like terms:

66 = 19z

Divide both sides by 19:

z = 66 / 19
z ≈ 3.47

Since we can't have a decimal number of golf holes, we will round z down to the nearest whole number:

z = 3

Now, substitute the value of z back into Equation 1 to find y:

y = 2z
y = 2(3)
y = 6

Finally, substitute the values of x and y back into Equation 2 to verify our results:

3x + 4y + 5z = 66
3(66 - 13z)/3 + 4(6) + 5(3) = 66
66 - 13z + 24 + 15 = 66
66 - 13z + 39 = 66
-13z + 39 = 0
39 - 13z = 0
13z = 39
z = 3

Therefore, the solution is:

x = 66 - 13z / 3 ≈ 66 - 39 / 3 ≈ 27 / 3 ≈ 9 (par-3 holes)
y = 6 (par-4 holes)
z = 3 (par-5 holes)

So, there are 9 par-3 holes, 6 par-4 holes, and 3 par-5 holes on the golf course.