Question

5x + 8y = -1
6y - x = 4y - 7

Answer 1

5x + 8y = -1
6y - 4y - x = -7 =>> 2y - x = -7

5x + 8y = -1  | *1 =>> 5x+8y= -1
2y - x = -7     | *5 =>> -5x + 10y = -35

5x+8y= -1 ditambah -5x + 10y = -35 menjadi 18y=-36
y=-36/18
y=-2          nilai y= -2

mencari nilai x => 5x+8y=-1
                      => 5x+8(-2)=-1
                      => 5x-16=-1     
                      => 5x=-1+16 =>> 5x=15
                      => x=15/5 =>> x=3
maka nilai x = 3

Answer 2

X=3
y=-2
caranya disubsitusikan persamaan 1 dan 2