Question

Solve using elimination method
7x+15y=32
X-3y=20

Answer 1

{7x+15y=32
{x-3y=20 /*5

{7x+15y=32

{ 5x-15y=100 (+)

7x+5x+15y-15y=32+100

12x=132 /:12

x=11

x-3y=20

11-3y=20 /-11

-3y= 9 /:(-3)

y=-3

The solution: (11; -3)

Answer 2

1. 7x+15y=32
2. x-3y=20/*5
2. 5x-15y=100
1.+2.= >12x=132
x=11
1. 7*11+15y=32
15y= -45
y= -3
x=11;y=-3