Solve the simultaneous equations E.g. 2x + y = 18 and x − y = 6.

Simultaneous equations can be solved in many ways. The two main ways are "solving for x and y" and the other is "substituting for x and y". Because in this example we are given "linear" equations (ask student if they know the difference between linear and quadratic), we will use the latter method.
First rearrange x − y = 6 for x, (ask if they know how to do this), x=6+y. Then sub this into the first equation (again ask if they know how to sub) as follows 2(6+y) + y = 18. Next simplify this by "collecting all like terms" 3y=6, then "solve for y" by dividing by 3 thus y=2. Finally go back to the second equation and sub this y to find x as follows, x - (2) = 6, meaning x = 8. If there is time use the first equation to check your answer 2(8)+(2) = 18.