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

There are three methods for solving simultaneous equations: elimination, substitution and by using graphs.Elimination is a good method in this case as the y terms are equal in both equations. We just add the two equations together, and the y terms cancel because they have opposite signs, giving 5x = 15, which we can solve to find the value for x. If the y terms had had the same sign, we would have subtracted one equation from the other. We then sub the value for x into either of the equations and solve it to find the value for y.For substitution, we need to rearrange one equation to make either x or y the subject, then substitute the rearranged equation into the other. For example, we could rearrange the second equation to be y = 3x - 8, then sub this into the first equation to give 2x + 3x - 8 = 7, which we can solve to get x = 3. We then sub this value into either equation to find y.To solve by using graphs, you would plot both of the graphs on the same axes and find the point where they meet. Here both equations are true, so the coordinates of this point are the solutions. However, this only works easily if you have graph paper and the solutions are whole numbers.