penyelesaian dari sistem persamaan 2x - 5y = -16 dan 5x + 2y = -11 adalah x dan y. nilai 7x - 8y adalah...?

MAPEL = MATEMATIKA
KELAS = 8
BAB = SPLDV

eliminasi nilai x
2x - 5y = -16 |×5
5x + 2y = -11 |×2

10x - 25y = -80
10x + 4y = -22
____________-
-29y = -58
y = -58/-29
y = 2

subtitusi nilai y
5x + 2y = -11
5x + 2(2) = -11
5x = -11 - 4
5x = -15
x = -15/5
x = -3

nilai 7x - 8y :
= 7(-3) - 8(2)
= -21 - 16
= -37

semoga membantu

2x-5y = -16   x5
5x+2y = -11  x2

10x-25y = -80
10x+4y = -22
------------------- -
       -29y = -58
            y = 2 

10x+4(2) = -22
10x + 8 = -22
10x = -30
x = -3

7x-8y
7(-3)-8(2)
-21 - 16= -37