Primarily, we should attempt to make either the x or y values of either equation be the same value, or the equivalent negative value. This is so we can add or subtract the equations to leave us with one variable. In this case, we should multiply the first equation by 5 to leave us with 10x + 15y = 75, and multiply the second by 2, leaving us with 10x + 8y = 26.Then we should subtract the second equation from the first equation, leaving us with 7y = 49. By dividing both sides by 7, we find our first variable y. Y is therefore equal to 7.
Then if we look at the original question, y can be inserted into either of the equations. If we take the first one, the equation that results is 2x + (3*7) = 15. The three and the seven multiply so 2x + 21 =15. If we subtract 21 from both sides, the equation we are left with is 2x = -6. By dividing both sides by 2, the answer for variable x is -3.Thus the solution to the simultaneous equation is x = -3 and y = 7