Penyelesaian dari sistem persamaan LINEAR dua variabel 2x-5y=-16 dan 5x+2y=-11 adalah x dan y. Nilai 7x-8y adalah?

2x - 5y = -16 | × 5 | 10x - 25y = -80
5x + 2y = -11 | × 2 | 10x + 4y = - 22
___________________________–
-29y = -58
y = 2

2x - 5y = -16
2x - 5(2) = -16
2x - 10 = -16
2x = -6
x = -3

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

2x-5y=-16(x5)-> 10x-25y = -80
5x+2y=-11(2) -> 10x+4y =-22
----------------------- -
-29y = -58
y = 2
2x - 5y = -16
2x - 5(2) = -16
2x = -16 + 10
x = -6 ÷ 2 = -3
7x - 8y
= 7(-3)+8(2)
= -21+16
= -5

semoga membantu...