Solve the following simultaneous equations 7x - 6y =38 and 3x + 9y =-3

To solve these equations you first want to eliminate the same variable from each equation. In this question it is easiest to eliminate Y, to do this we will times equation 1 by 3 to get 21X-18Y=114 and equation 2 by 2 to get 6X+18Y=-6. Now, when you add both of or new equations together you get 27X= 108 which leads to X=4. We can now substitute X=4 into our 1st equation to find a value for Y. So, 7(4) -6Y= 38 implies that -6Y=10 hence Y=-5/3. To check your answer you can substitute X=4 and Y=-5/3 into the second equation to check the answer works, which it does.