3x+5y=56 (2)

3( 1)-(2)

3x+6y-3x-5y=63-56

Y=7, brought in (1)

x+ 14=2 1

x=7

So x=7, y=7.

7.5x+7y=52

5x+2y=22

( 1)-(2)

5y=30

Y=6, brought in (1), and obtained.

5x+42=52

5x= 10

x=2

So x=2 and y=6.

8.5x+5y=65 x+y= 13

7x+7y=203 x+y=29

No answer

9.8x+4y=56

x+4y=2 1

( 1)-(2)

7x=35

X=5, brought into (2)

5+4y=2 1

4y= 16

y=4

So x=5 and y=4.

10.5x+7y=4 1

5x+8y=44

(2)-( 1)

Y=3 brought in (1)

5x+2 1=4 1

5x=20

x=4

So x=4 and y=3.

1 1.7x+5y=54

3x+4y=38

4( 1)-5(2)

28x+20y- 15x-20y = 2 16- 190

13x=26

X=2 is brought in (2)

6+4y=38

4y=32

y=8

So x=2 and y=8.

12.x+8y= 15

4x+y=29

( 1)-8(2)

x+8y-32x-8y= 15-29×8

-3 1x=-2 17

X=7 into (2)

28+y=29

y= 1

So x=7 and y= 1.

13.3x+6y=24

9x+5y=46

3( 1)-(2):

9x+ 18y-9x-5y=72-46

13y=26

Y=2 is brought in (2)

9x+ 10=46

9x=36

x=4

So x=4 and y=2.

14.9x+2y=62

4x+3y=36

3( 1)-2(2)

27x+6y-8x-6y= 186-72

19x= 1 14

X=6 brought in (2)

24+3y=36

3y= 12

y=4

So x=6 and y=4.

15.9x+4y=46

7x+4y=42

( 1)-(2)

2x=4

X=2 introduction (1)

18+4y=46

4y=28

y=7

So x=2 and y=7.

16.9x+7y= 135

4x+y=4 1

7(2)-( 1)

28x+7y-9x-7y=287- 135

19x= 152

X=8 brought in (2)

32+y=4 1

y=9

So x=8 and y=9.