Question

Solve the system of equations.
7x+3y=−25

−7x+9y=−47

Answer 1

Add the equations to eliminate x:
(7x+3y)+(-7x+9y)=−25+−47 ⇒ 12y = −72 ⇒ y = −6.

Substitute y into 7x+3y=−25:
7x + 3(−6) = −25 ⇒ 7x − 18 = −25 ⇒ 7x = −7 ⇒ x = −1.

Solution: (x, y) = (−1, −6).