**QUESTION:** Tom measures himself to be 182cm tall and calculates that this new height is a 4\% increase on his height 2 years ago. Work out how tall Tom was 2 years ago.

**ANSWER:** We need to consider how we would calculate a 4\% increase. We know that 4\%=0.04, so we get the multiplier for a 4\% increase to be

1+0.04=1.04

Let H be Tom’s height from two years ago. We know that the result of multiplying H by 1.04 must be 182. We can write this as an equation:

H\times 1.04=182

Then, if we divide both sides by 1.04 we get

H=182\div 1.04=175

So, Tom’s height two years ago was 175cm.