Question 515775

1.)
x + 2y = -1............(1)
4x - 5y = 22...........(2)

Multiply (1) by -4 and add to (2)

-4x-8y=4
4x-5y=22
-13y=26
-13y/-13=26/-13
y=-2
Put the value of y in (1)
x+2y=-1
x+2(-2)=-1
x-4=-1
x=-1+4
x=3

x,y = 3, -2

Check 
Put the values of x and y in (1)
x + 2y = -1............(1)
3+2(-2)=-1
3-4=-1
-1=-1


2.)
-3x + 7y = 14 ..........(1)
2x -  y = -13...........(2)

Multiply (2) by 7 and add to (2)
-3x + 7y = 14
14x - 7y = -91
--------------
11x=-77
11x/11=-77/11
x=-7

Put the value of x in (2)
2x -  y = -13...........(2)
2(-7)-y=-13
-14-y=-13
-y=-13+14
-y=1
y=-1

x,y=-7,-1

Check
Put the values of x and y in (2)
2(-7) - (-1) = -13
-14 + 1 = -13
-13=-13