Solve each system of equations by the substitution method. Show your work.

  1. y = 8
    7x = 1 - y

  2. y = x - 1
    4x - y = 19
Hi,

The "substitution method" is exactly what the words say. For problem 1 take the value given for y, y = 8 and "substitute" it into the second expression. Thus the second expression becomes

7x = 1 - 8 Now solve for x.

Again for the second example. You are given y = x - 1 so replace (substitute) the "y" in the second expression by x - 1. Thus

4x - y = 19 becomes

4x - (x - 1) = 19 Solve for x.

Cheers,
Penny
Go to Math Central