joe is going to build a retangular lap pool. the perimeter of the pool will be 240 feet. the length of the pool will be 20 feet more than 3 times the width. find the length and width

L=3W+20

P= 2L + 2W= 2(3W+20)+2W
240= 8W+40

check that. Solve for W, then solve for L

tom is going to build a fence around his garden which is rectangle measuring 8 cm by 20 m. he will first put in posts which will be 4 m apart. if the post cost $4 each what will be the total cost for all the posts

To find the length and width of the rectangular lap pool, we can start by setting up equations based on the given information.

Let's assume:
- Width of the pool = w
- Length of the pool = l

According to the given information:
1. The perimeter of the pool is 240 feet.
The perimeter of a rectangle is calculated by adding up the lengths of all four sides. In this case, it would be:
2 * (length + width) = 240

2. The length of the pool is 20 feet more than 3 times the width.
This can be expressed as:
length = 3w + 20

Now, we can solve these two equations simultaneously to find the values of the length and width.

From equation 1, we can rewrite it to isolate just the length:
2 * (l + w) = 240
l + w = 120

Substitute the value of l from equation 2 into the rewritten equation above:
3w + 20 + w = 120
4w + 20 = 120
4w = 100
w = 25

Now we can substitute the value of w back into equation 2 to find the length:
l = 3w + 20
l = 3(25) + 20
l = 75 + 20
l = 95

Therefore, the width of the rectangular lap pool is 25 feet, and the length is 95 feet.