Solve the following pair of simultaneous equations; 10x+4y=15, 2x+y=7
So, to solve these equations, you must choose the variable you want to work with, in this case let's go with y. Make sure that you write out every step of your working so it is easy to follow and minimises mistakes. As we are focusing on y, lets re-arrange the second equation to y=7-2x. Now we can just substitute this into the first equation: 10x+4(7-2x)=15. Now we are left with one variable which allows us to find out its value. Expanding the bracket it gives us: 10x+28-8x=15. Tidying it up gives us: 2x=-13, which gives us x=-13/2. Leave it in the fraction form rather than decimal as it is easier to work with. Now, we know the x value, we insert that back into the second equation: 2(-13/2) +y=7, -13+y=7, y=20. To check your answer is correct, put these values into first equation with x and y values: 10(-13/2)+4(20)=15, -65+80=15, 15=15.
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