Question

Which ordered pair is a solution to the equation 3x+5y=9???

Answer 1

Here, you just plug in numbers and see if both sides of the equation are equal in the end.

But first, why don't we simplify the given equation. 

3x+5y=9
5y=-3x+9

Of course we like to write that in this form:

$y= -\frac{3}{5}x + \frac{9}{5}$

But it's not an efficient equation if you want to plug in points.

So we use 5y=-3x+9.

Plug in answer choices:

A. 5 x 3 = (-3)2 + 9
B. 5 x 3 = (-3)(-2) + 9
C. 5 x (-3) = (-3)(-2) + 9
D. 5 x (-3) = (-3)2 + 9

Simplify.
A. 15 = -6+9
B. 15 = 6+9
C. -15 = 6+9
D. -15 = -6+9

Finish the right side of the equation, where we get:
A. 15 = 3
B. 15 = 15
C. -15 = 15
D. -15 = 3

The only valid equation here is Choice B.