How do I solve simultaenous equations? e.g. 2x -5y =11 and 3x+2y=7

Step 1: Multiply both equations together so that the multiples of one of the unknown terms are the same or the negative of that number. This will allow you to add/subtract the two equations to eliminate one of the unknowns. Remember you are multiplying the whole of the equation so each term must be mutliplied. 

Step 2: once you have eliminated one of the unknown terms (e.g. y) you can easily solve the equation to find the other unknown term (e.g. x) by rearraning the equation to make it the subject . 

Step 3: Once you have found one of the unknowns, you can substitue your answer into one of the equations, and solve the equation to find the answer to the other unknown.