Question

If y varies directly as x and y =15 when x=3, find y when x=12

Answer 1

y=kx
15=k3
k=5
so y=5x
when x=12 y=5*12=60

Answer 2

how did you get that?

Answer 3

and which on is the answer?

Answer 4

y=kx
this is general form of direct variance. So you need to find constant k. To do that use initial values y =15 when x=3. Plug them and find k. Rest is easy.
answer is y=60

Answer 5

ohk