3.10 Formulae Involving all Operations

This is the crunch time: time to put everything together. If you've managed up until now, one more small step and you're there.

It’s sometimes difficult to give rules which will cover every eventuality, but as a rule of thumb, for the formulae you can cope with so far:

1. Get rid of fractions either by multiplying both sides by the denominator (if there is only one), or by multiplying both sides by the lowest common multiple of the denominators, often the product (if there is more than one).

2. Move terms around from side to side so as to isolate on one side the term involving the variable you want (where it is positive) and have all the other terms on the other side. This involves changing side/sign if there are + and – signs involved.

3. Finally, isolate the variable you want, probably by division.