Elimination Method:

The equations are

              Equation (1)

               Equation (2)

Since the coefficients of the m-terms are same, you can eliminate these terms by subtracting the equations. Subtract the equations to eliminate variable m.

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

Apply division property of equality: if a = b then 

                                 (Divide each side by 3)

                                      (Cancel common terms)

                                         (Divide: )

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

          (Equation 1)

                            (Multiply: )

            (Add 20 to each side)

                      (Apply additive inverse property: )

                            (Apply additive identity property: )

                                      (Add: )

                                 (Divide each side by 2)

                                      (Cancel common terms)

                                           (Divide: )

The solution is .