Question

{5×+2y=-45
{9×-5y=5}

Answer 1

{5×+2y=-45    ==>2y=-45-5x ==>y=(-45-5x)/2

 {9×-5y=5

9x-5*(-45-5x)/2=5

multiplique tudo por 5

45x-5*(-45-5x)=25

45x+225+25x=25

80x=-200

x=2,5

y=(-45-5x)/2  ==>y=(-45-5*2,5)/2 =-28,75

Answer 2

5x+2y=-45x(5)
9x-5y=5 x(2)
---------------
25x+10y=-225
18x -10y = 10
43x = -215
x= -215/43=-5
---------------------
5x +2y=-45
5(-5)+2y=-45
-25+2y = -45
2y= -45+25
y=-20/2=-10