CPM Homework Help : CC2MN Problem 4-65

State whether or not each equation below represents a proportional relationship. How can you tell?

Hint:

Equations that represent proportional relationships contain only multiplication.

$y=x+2.3$
Answer (a):
Not proportional, since there is a $y\text{-intercept}$ other than $0$ .

$y=\frac{6}{13}x$
Hint (b):
Is there anything other than multiplication in this equation?

$7-y=2x$
Hint (c):
This equation can be rewritten as $y=-2x+7$
Answer (c):
Not proportional. Why?