Question

If x and y are in direct proportion and y is 80 when x is 10, find y when xx is 15.

Answer 1

120

Explanation:

set up a proportion: 80/10=y/15

solve: 80*15=10y

1200=10y

y=120

Answer 2

y = 120

Explanation:

If x = y, they can be written as a fraction to show their proportionality as
`(10)/(80)`. This is equal to
`(1)/(8)`, so when x = 1, y = 8. To find when y is equal to x when x = 15, just multiply y by 15. 15(8) = 120, so y = 120 when x = 15.