The equations are

                             Equation (1)

                             Equation (2)

Since the coefficients of the s-terms are additive inverses, you can eliminate

these terms by adding the equations. Add the equations to eliminate variable t.

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

                           (Divide each side by 2)

                               (Cancel common terms) \ \

                                  (Divide: )

Now Substitute 3 for s in either equation to find the value of t.

                             (Equation 1)

                             (Replace s by 3)                                

                 (Subtract 3 from each side)

                 (Commutative property: )

                         (Additive inverse property: ) \ \

                               (Subtract: )

                 (Multiply each side by negative one)

                              (Product of two same signs is positive) \ \

The solution is .

The solution is .