-x+y=5

The following formula ×2+ the above formula, eliminate x, get.

3y = 12, so y = 4.

x=y-5=- 1

So the solution of the equation is x =- 1 and y = 4.

(2){x-2y=3

x+2y=6

The following formula+the above formula, eliminate y, get.

2x = 9, so x = 9/2.

y=(6-x)/2=3/4

Therefore, the solution of the equation is x = 9/2 and y = 3/4.

(3){x+y=36

x+2y=50

The following formula-the above formula, eliminate x, get.

y= 14，x=36-y=22

Therefore, the solution of the equation is x = 22 and y = 14.

(4){5x-6y= 1

2x-6y= 10

Upper formula-lower formula, eliminate y, and get

3x =-9, so x =-3.

y=(5x- 1)/6=-8/3

So the solution of the equation is x =-3 and y =-8/3.

(5){2a-b=8

3a+2b=5

The following formula+the above formula× 2, b is eliminated, so.

7a=2 1，a=3

b=2a-8=-2

Therefore, the solution of the equation is a = 3 and b =-2.

{2x+3y=-5

3x-4y= 18

The following formula ×3+ the above formula ×4, eliminate y, and get.

17x=34，x=2

y=(3x- 18)/4=-3

Therefore, the solution of the equation is x = 2 and y =-3.