Question

quanto é2x+5y=13
             -2x+7y=23

Answer 1

 2x + 5 y = 13
-2x + 7 y = 23
___________
00  + 12y = 36
y = 36/ 12
y = 3 

2x + 5 y = 13
2x + 5(3)= 13
2x + 15 = 13
2x= 13 - 15
2x = -2
x= -2/2
x= -1