Elimination Method:

The equations are

              Equation (1)

            Equation (2)

Since the coefficients of the b-terms are same, you can eliminate these terms

by subtracting the equations. Subtract the equations to eliminate variable b.

Write the equations in column form and subtract the corresponding columns.

.

Now, find the b value by substituting in either equation.

                  (Equation 1)

                          (Multiply: )

         (Add 15 to each side).

         (Apply commutative property of addition: )

                       (Apply additive inverse property: )

                             (Apply additive identity property: )

                                   (Add: )

The solution is .