Question

\frac{f+3}{12}=\frac{7}{2}
cross multiplying

Answer 1

\[\frac{ f+3 }{ 12 }=\frac{ 7 }{ 2 }\]
when we cross multiply, we multiply in a cross direction like this:

Answer 2

to finish solving this, distribute the 2 across f+3, then solve for f