Question

 Use substitution to solve the system.   x=3y+7 and 3x-4y=16




x=
y=

Answer 1

x = 3y + 7
3x - 4y = 16

Substituting the value of x,

3(3y + 7) - 4y = 16

9y + 21 - 4y = 16

5y + 21 = 16

5y = -5

Thus, y = -1.

Substituting the value of y,

x = 3y + 7

x = -3 + 7

Thus, x = 4.

Thus, x = 4, and y = -1

Answer 2

First we already know x, so we can put it into the other equation like so:

3(3y+7)-4y=16

Then we can solve it.

9y+21-4y=16

5y=-5

y=-1

Then we can find x.

x=3y+7

x=3(-1)+7

x=-3+7

x=4

Hope I helped!