Question

find the solution to the system of equations by the addition method.

-5x-7y=-57
-0.9x + 0.7y= -11.2
0.1x + 0.7y = -4.2

Answer 1

ignore the -5x part

Answer 2

-0.9x + 0.7y= -11.2
0.1x + 0.7y = -4.2
- - +
==============
-1.0x + 0 = -7

-x = -7

x = 7

Answer 3

Now, substitute it in any equation, you will get the value for y