To find out how much Quadra spent, we can use this equation:
- Total amount of money × fraction spent = amount left
Fitting the numbers into the equation would look like this:
Why do we multiply by 0.75?
We multiply by 0.75 because it is equivalent to 3/4.
If we now know that Quadra spent £90, we can subtract that from her total amount of money to get the amount of money she saved.
Therefore, Quadra saved £30.