Question

15. 5x – 2y = -19
8x + 5y = -55

Answer 1

x = -5

y = -3

Explanation:

5x – 2y = -19 (1)

8x + 5y = -55 (2)

<=> 5(5x – 2y) = 5(-19)

2(8x + 5y) = 2(-55)

<=> 25x - 10y = -95 (3)

16x + 10y = -110 (4)

Add (3) and (4), we have:

25x - 10y + 16x + 10y = -95 -110

<=> 41x = -205

=> x = -5

Replace x = - 5 in (1), we have:

5(-5) – 2y = -19

<=> -25 - 2y = -19

=> y = [-25 - (-19)]/2 = -3