Question

What should you multiply the entire equation by when there are fractions?

Answer 1

the denominators

example

\[\frac ab=\frac cd\]
multiplying by the denominator of the lefthand side
\[\frac ab\times b =\frac cd\times b\\a=\frac{bc}d\]
now multiplying by the denominator of the righthand side
\[a\times d=\frac{bc}d\times d\\ad=bc\]

Answer 2

the fractions have gone away!

Answer 3

a numerical example

\[\frac x4=\frac32\\
\frac x4\times2=\frac32\times2\\
\frac x2=3\\
\frac x2\times2=3\times2\\x=6\]