Question

y varies directly with x, and y = 2 when x = 5.

What is the value of x when y = 15?

Answer 1

@jim_thompson5910

Answer 2

y varies directly with x

so this means

y = kx

where k is some fixed number

Answer 3

we are told that

y = 2 when x = 5

so

y = kx

2 = k*5

solve for k

Answer 4

so 6?

Answer 5

when you solved for k, what did you get

Answer 6

wait how do i solve for k

Answer 7

2 = k*5

divide both sides by 5 to isolate k

Answer 8

k = ???

Answer 9

2.5?

Answer 10

you divided in the wrong order

Answer 11

0.4?

Answer 12

good,

so

y = kx

turns into

y = 0.4x

Answer 13

now you want to find x when y = 15, so

y = 0.4x

15 = 0.4x

now solve for x

Answer 14

37.5?

Answer 15

you nailed it

you can also represent 37.5 as the fraction 75/2

Answer 16

so x = 37.5 or x = 75/2

Answer 17

ok thank you(:

Answer 18

you're welcome