solve using the addition method.

#1

x+y=4
2x-y=5

#2

x+2y=9
3x-2y=-5

#3

x-y=8
2x+y=7

#4

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

#5

2x+3y=8
5x+2y=-2

#6

5x-2y=2
3x