Question

Solve the system of equations -8y+9x = -5; 8y+7x = -75

Answer 1

`\boxed{x=-5}\\ \boxed{y=-5}`

Explanation:

-8y + 9x = -5

8y + 7x = -75

Add the equations (eliminating the y-variable).

16x = -80

Divide both sides by 16.

`(16x)/(16)` =
`(-80)/(16)`

x = -5

Plug x as -5 in the first equation to find y.

-8y + 9(-5) = -5

-8y +-45 = -5

Add 40 to both sides.

-8y = 40

Divide both sides by -8.

`(-8y)/(-8)` =
`(40)/(-8)`

y = -5

Answer 2

x = -5

y = -5

Explanation:

-8y+9x = -5; 8y+7x = -75

Add the two equations together to eliminate y

-8y+9x = -5

8y+7x = -75

----------------------

0y + 16x = -80

Divide each side by 16

16x/16 = -80/16

x = -5

Now find y

8y+7x = -75

8y+7(-5) = -75

8y-35 = -75

Add 35 to each side

8y = -40

Divide by 8

8y/8 = -40/8

y = -5