Solve the Simultaneous equation: 4x+y=25, x-3y=13

Firstly, try and make one of the variables (x or y) the same in both equation, in this instance because we have a positive and negative y if we add them, they will cancel out. Therefore multiply the first equation by 3 so we have 3y on both equations, giving us 12x+3y=75. Now we can add both equations together, which eliminates the y (-3y+3y = 0) leaving with 13x = 91. Now we simply find x by dividing 91 by 13 and getting an answer of x = 7. Now that we know x = 7 we can simply sibstitiute into any equaton, to find out the answer. For ease I will use the first equation. As x = 7, 4x = 28 so therefore 28 + y = 25. To find y we simply subtract 28 from both sides leaving us with y = -3. X = 7, Y = -3