How do you solve 3y - 2x = 11 and y + 2x = 9 using substitution?

1 Answer
Mar 10, 2018

y=5 and x=2#

Explanation:

2x + y =9
-2x + 3y =11

We need to solve 2x + y = 9 for y

2x + y = 9
y=9 -2x

Now substitute -2x + 9 for y in -2x + 3y =11

-2x + 3y =11

-2x + 3(-2x+9)=11

Distribute

-2x + (3)(-2x)+(3)(9)=11

-2x - 6x + 27 = 11

-8x + 27 = 11

-8x = 11 - 27

-8x = -16

x=(-16)/(-8)

x=2

Now substitute 2 for x in y=-2x+9

y=-2x + 9

y=-2(2)+9

y=-4 + 9

y=5

Thus,

The answers are y=5 and x=2