The equations are

                   Equation (1)

                     Equation (2)

Multiply the equation (1) by 5.

             Equation (3) 

Multiply the equation (2) by 4.

               Equation (4) 

Subtract the equation (3) and equation (4) to eliminate the x variable

          (Subtraction the corresponding columns)

Apply division property of equality: if a = b, then.

Divide each side by 9.

Substitute  in equation (3).

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

Subtract 200 from each side.

Apply Additive inverse property: .

Apply Additive identity property: .

Apply division property of equality: if a = b, then.

Divide each side by 20.

The solution is .

The solution is .