Elimination method:

Given equations are,

----------(1)

----------(2) 

First equation has multiply each side by 4.  

               (First equation)

   (Apply distributive property: )

                    (Multiply: )

                               (Multiply: )

--------(3)

(2) and (3) equations when the coefficients of a variable and are same,

subtracting the equations will eliminate the variable. Subtracting (2) and (3) equations will eliminate the variable y.

       (Subtracting (2) and (3) equations)

Apply division property of equality: If a = b then .

                  (Divide each side by 0.4)

                           (Cancel common terms)

                               (Divide: )

Substitute for x in either equation to find y.

                        (Second equation)

               (Substitute )

                            (Multiply: )

Apply commutative property of addition: .

          (Subtract 81 from each side)

                    (Apply additive inverse property: )

                         (Apply additive identity property: )

                            (Subtract: )

Check the solution:

To Check, substitute and  in either equation.

                             (Second equation)

               (Substitute and  )

                        (Multiply: )

                                         (Subtract: )

The solution  is true.

The solution is .