Question

2x+3y=13
5x-y=7
?????

Answer 1

2x + 3y = 13
3 y = 13 - 2x
y = (13 - 2x)/3

5x + (( 13 - 2x) /3) = 7
mmc = 3

(15 x + 13 - 2 x ) / 3 = 7
13 x + 13 = 7 . 3
13 x = 21 - 13
13 x = 8
x = 8/13

y = (13 - 2.(8/13) ) / 3
y = ( 13 - (16/13)) / 3
mmc = 13
y = ((169 - 16) / 13) / 3
y = (153/13) / 3
Mantém a primeira e inverte a segunda
153/13 . 1/3
y = 153 / 39
y = 3,9