how to solve this

Question

-x_8y=19

-3x+24y=57

solve by substitution

Answer 1

you could rewrite as follows, changing signs in #1 and /3 in #2:

x + 8y = -19

-x + 8y = 19

I would prefer to solve by adding these 2 equations to get 16y = 0, y = 0. Then from #1, x = -19.

However, they ask for substitution, so from #1 you get x = -8y - 19. Then substitute in #2 to get

8y +19 + 8y = 19

16y = 0

y = 0

Again, from #1, x = -19

Answer 2

-x - 8y = 19

-3x + 24y = 57

Looking at both equations, top is easier to solve for one variable.

-x - 8y = 19

+8y +8y

-x = 8y +19

Divide both sides by -1.

x = -8y - 19

Plug x into second equation and solve for y.

-3(-8y -19) + 24y = 57

-3*(-8)y -3*(-19) + 24y = 57

24y + 57 + 24y = 57

48y + 57 = 57

48y = 0

y = 0

Plug y into first equation.

-x - 8*(0) = 19

-x = 19

x = -19

Answer @ (-19, 0)

Plug point into either equation to verify.

-3(-19) + 24(0) = 57

57 = 57