To find the original bill, you need to divide the amount paid by the percentage paid. Since the tip was 21.5% on top of the full amount already, we know she paid 121.5%. So we can divide the cost by that.
First we need to find the base, which is 6 and the height which is 7. Then, multiply 6 and 7 to get 42. Then add your units, which are meters. So, 42m is your answer. I hope this helps! :)
