A postal clerk sold some 15c stamps and some 25c stamps .altogether ,15 stamps were sold for a total cost of S3.15 .how many of each type of stamps were sold?
x+y = 15
15x+25y = 315
Now just solve for x and y.
To solve this problem, we can use a system of equations.
Let's say the number of 15c stamps sold is represented by 'x' and the number of 25c stamps sold is represented by 'y'.
We know the following information:
1. The total number of stamps sold is 15:
x + y = 15
2. The total cost of the stamps sold is $3.15:
0.15x + 0.25y = 3.15
Now, we can solve this system of equations to find the values of 'x' and 'y'.
Method 1: Substitution
- Solve the first equation for 'x':
x = 15 - y
- Substitute this value of 'x' into the second equation:
0.15(15 - y) + 0.25y = 3.15
2.25 - 0.15y + 0.25y = 3.15
0.1y = 0.9
y = 9
- Substitute the value of 'y' back into the first equation to find 'x':
x + 9 = 15
x = 6
Therefore, 6 of the 15c stamps and 9 of the 25c stamps were sold.
Method 2: Elimination
- Multiply the first equation by 0.15 to make the coefficient of 'x' equal to 0.15:
0.15x + 0.15y = 2.25
- Subtract this equation from the second equation:
(0.15x + 0.25y) - (0.15x + 0.15y) = 3.15 - 2.25
0.1y = 0.9
y = 9
- Substitute the value of 'y' back into the first equation to find 'x':
x + 9 = 15
x = 6
Therefore, 6 of the 15c stamps and 9 of the 25c stamps were sold.