Question

quanto é {3x-4y=8
{-x-4y=77

Answer 1

3X - 4y = 8 . (-1)
-X - 4y = 77
-3X + 4y = -8
-X - 4y = 77

-4X = 69
X = 69 / 4
X= 17,25

-17,25 - 4y = 77
-4y = 77 + 17,25
-4y = 94,25
y= 94,25/4
y =23,5625