By doubling each dimension, the area of a parallelogram increased from 36 square centimeters to 144 square centimeters. How do you find the percent increase in area?
Once you start to recognise the connections between numbers you will be able to do these much quicker than I have shown.
We are only interested in the change in area. As both these values are given then anything else is a 'red herring'.
Assuming the increase is to be measured against the original area
Notice that for 108 that
Notice that for 36 that
So to simplify we have:
Let the unknown value be
Then we are looking to end up with
To change 1 into 100 multiply by 100. What you do to the top you do to the bottom.
So we have the percentage