The equations are

Multiply the first equation by 20

Now the equation is

               Equation (1)

Multiply the second equation by 15

Now the equation is

                  Equation (2)

Since the coefficients of the y-terms, +300 and –300, are additive inverses,

you can eliminate these terms by adding the equations.

Add the equations to eliminate variable y.

    (Write the equations in column form and add)

Apply division property of equality: Divide each side by 35.

                           (Cancel common terms)

                             (Divide: )

Now Substitute in either equation to find the value of y.

    (Equation 1)

             (Multiply: )

Apply addition property of equality: Add 60 to each side.

Apply commutative property of addition: a + b = b + a.

              (Apply additive inverse property: )

                       (Add: 15 + 60 = 75)

Apply division property of equality: Divide each side by 15.

                   (Cancel common terms)

                        (Divide: )

The solution is .

The solution is .