Question

Y varies directly as x. y=40 when x=4. Find y when x=15.

Answer 1

150

Explanation:

Y varies directly, so we know the rule will stay the same.

if y=40 when x=4, then the equation for y is

y = 10x

so if x = 15

y=10(15)

y=150

Answer 2

Answer: x=150

Explanation:

40/4= 10

So the formula for y must be x(10)

15(10)= 150