Question

The graph of a proportional relationship passes through (9,18) and (1,y). Find y.

Answer 1

y=2. The scale factor is 9, and if you divide 18 by 9, you get 2.

Answer 2

(9,18) (1,y)

   9          1
____ = ____
 18          y

cross multiply
9y=18
divide both sides 9
y=2

(9,18) (1,2)