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.