2x-2y=12 from 8x-11y=78

Question

solving linear systems of equation

Answer 1

2x -2y = 12--------------(1)

8x - 11y = 78 -----------(2)

4 * (1);

8x - 8y = 48 -------------(3)

(2)  - (3);

you will get,

- 3y = 30

  y = - 10;

substitute y = - 10 in (1), you wil get

2x - 2*(-10 ) = 12

2x +20 = 12

2x = 12 - 20

2x = - 8

x = -8/2

x = -4;

therefore x = -4; y = -10