I need help with the work of the math

13) (-2,-3)  14) (7,-4)   15) (-8,7)

Step-by-step explanation:

13) y=8x+13

   -4x-5y=23

use substitution

-4x-5(8x+13)=23

distribute -5 in the parenthesis

-4x-40x-65=23

-44x-65=23

add 65 on both sides

-44x=88

divide both sides by -44

x=-2

for y...

y=8(-2)+13

y=-16+13

y=-3

answer is (-2,-3)

14) -3x-y=-17

y=-4x+24

use substitution

-3x-1(-4x+24)=-17

distribute the -2 in the parenthesis

-3x+4x-24=-17

x-24=-17

add 24 on both sides

x=7

for y...

y=-4(7)+24

y=-28+24

y=-4

answer is (7,-4)

15)5x+4y=-12

   y=-2x-9

use substitution

5x+4(-2x-9)=-12

distribute 4 in the parenthesis

5x-8x-36=-12

-3x-36=-12

add 36 on both sides

-3x=24

divide both sides by -3

x=-8

for y...

y=-2(-8)-9

y=16-9

y=7

answer is (-8,7)