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Given an equation of the form $a/b=c$, how do you move $a$, the numerator, over to the other side so that you get $b =c?$ (where $?$ denotes my ignorance of what the right side should look like).

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up vote 14 down vote accepted

$$\begin{align*} a/b &= c\\ a &= bc\\ b &= a/c \end{align*}$$

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I know this has been answered but here is it worded. You multiply the denominator out by multiplying both sides so: a/b = c becomes a/bb = cb. As you are multiplying the fraction by the denominator the denominator and the multiplier cancel out and you are left with a = bc. You cannot get rid of a letter but if you wanted b on one side then you would simply move c, to do this you factorise so its a = b(c). You then divide both sides by c, so then a/c = (b(c))/c. Then the c on the numerator and denominator cancel out so you will be left with a/c = b or rearrange to b = a/c.

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