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

"'y' varies directly as 'x' " means

y = (a number) times 'x'

and it's always the same number.

You said that 'y' is 15 when 'x' is 3.

y = (a number) times 'x'

15 = (a number) times 3

Divide each side by 3:

(the number) = 15/3 = 5

Now we know that [ y = 5x ].

So when 'x' is 12, y = 5x = 60.

If x1=3 and x2=12 then that would mean that you would need to multiply y1 by 4 since 3*4=12

15*4=60 which would mean the y variable it is asking in this question is 60