Answer: One way to calculate the percent increase in Robin's monthly bill is to use the following formula:
% increase = (new amount - original amount) / original amount x 100
In this case, the original amount is $120 and the new amount is $150. So, the calculation would be:
% increase = (150 - 120) / 120 x 100 = 30 / 120 x 100 = 0.25 x 100 = 25
Therefore, the percent increase in Robin's monthly bill is 25%.
Another way to calculate the percent increase is to use the formula:
(New amount - original amount) / original amount
In this case: (150-120)/120 = 0.25, and multiply by 100 to get 25%
So, both formula gives the same answer 25%
Explanation: