Question

Suppose y varies directly with x and y = 3 when x = 12. what is the value of y when x = 40

Answer 1

y varies directly with x

so y = kx

y = 3 when x = 12 then 3 = 12k so k = 3/12 = 1/4

If x = 40 then

y = kx

y = 1/4( 40)

y = 10

Answer

y = 10 when x = 40

Answer 2

10 because if you divide 12 by 3 it will give you 4 x=4 and 3 by itself and you would get y=1 in order to get 40 you will have to multiple for by 10 and multiply y by 10