y - 5 = x, 4x - y = 4 solve by substitution

Question

can you solve the two equations by the substitution method

 

Answer 1

y - 5 = x

4x - y = 4

 

Since y-5 = x, substitute y-5 in place of x in the second equation:

 

4x- y = 4

4(y-5) - y = 4

4y - 4*5 - y = 4

3y - 20 = 4

3y = 24

y =8

 

Solve for x:

 

y - 5 = x

8-5 = x

3 = x

 

Check:

4x - y = 4

4(3) - 8 = 4

12 - 8 = 4

4 = 4

Check

 

y - 5 = x

8 - 5 = 3

3 = 3

Check!

Answer 2

y-5=x

4x-y=4

4(y-5)-y=4

4y-20-y=4

3y-20=4

3y=4+20

3y=24

y=24/3

y=8

8-5=x

3=x

x=3 and y=8