Question

Use substitution to solve the system. x-2y=7 2x+5y=5 X= Y=

Answer 1

from first equation x = 7 + 2y. Substitute this into second equation:-

2(7 + 2y) + 5y = 5

9y = -14 + 5 = -9

y = -1

Plug this into the first equayion

x - 2(-1) = 7

x = 5

Answer is x = 5, y = -1 .

Answer 2

Let’s solve x-2y=7 first.

Add 2y from both sides.

X=2y+7

Substitute x=2y+7 in 2x+5y=5 for x.

2(2y+7)+5y=5

Simplify.

9y+14=5

Subtract 14 from both sides.

9y=-9

Divide 9 from both sides

y=-1

Substitute the y in x-2y=7

x-2(-1)=7

x=5

ANSWER: x=5, y=-1