Ben is hoping to enter the long jump at his school sports day.  
One day I saw him manage quite a good jump.
However, after practising several days a week he finds that he can jump half as far again as he did before.
This last jump was $3.75$ metres long.
So how long was the first jump that I saw?
 

Now Mia has been practising for the high jump.
I saw that she managed a fairly good jump, but after training hard, she managed to jump half as high again as she did before.
This last jump was $1.20$ metres.
So how high was the first jump that I saw?
 
How did you work these out?
Can you find any other ways of finding a solution?
Which way do you prefer?  Why?