For this case we can use the following rule of three: $ 500 ---------> 100% $ 400 ---------> x Clearing x we have: x = (400/500) * (100) = 80% Therefore, the percentage of decrease in the rent is: p = 100-x p = 100-80 p = 80% Answer: a proportion can be used to calculate p is: p = 100 - ((400/500) * (100))
