Question

Five times the first number added to the second number is -21

Two times the first number added to the second number is -9​

Answer 1

let the first number be x

second number be y

5*(x)+y=-21---------->equation 1

2*(x)+y=-9------------->equation2

eq1 * 2:

2(5x+y)=2*-21

10x+2y=-42

eq2 * 5:

10x+5y=-45

10x+2y=-42

-(10x+5y=-45)

-----------------

0 - 3y=3

y=3/-3

y=-1

sub y=-1 in eq1;

5x+y=-21

5x+ -1=-21

5x-1=-21

5x=-21+1

5x=20

x=20/5

x=4

y=-1