Solve the simultaneous equations 2x + y = 7 and 3x - y = 8.

While there are several ways to solve this, in this particular case I would favour the method of elimination. Since the value of y is the same and they have opposite signs, we can add the equations together to eliminate the y value. This reads as 5x = 15 (add the x parts togther etc), as y + -y = 0. The divide by 5 to obtain x so we find x = 3. To find y, substitute the x value found into one of the equations and solve. 2(3) + y = 7. Thus y = 1.