15. 5x - 2y = - 19

8x + 5y = - 55

x = - 5

y = - 3

Step-by-step 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