Solve the simultaneous equations: 15x+10y=20 4x+5y=17

To explain this question to a student, I would initially ask my own questions in order to gain an understanding of what the student already knows about simultaneous equations. I would ask if they had seen similar questions to this before and whether they had some idea of what methods we could use to answer it. Once I had established which part of the quetion the student is strugggling with, I would begin my explanation. Depending on what methods the student has already learnt, or whether they have learnt any at all, I would probably advise using the elimination method for this question as it is clear that the coefficients of y in both equations are multiples of each other. We would multiply the second equation by 2 in order to obtain 8x+10y=34. I would then subtract the second equation from the first equation to get: 7x=-14. Therefore, x=-2. I would then substitue x=-2 into one of the equations to obtain y=5. In order to ensure the answer is accurate, I would recommend that the student always checks their answer to the question using the other equation.