What is the inverse of addition

The last time i bought this product , it cost $20.00 but it looks like it cost 29. 60 today? what is the increase

Every time you drive you will experience a combination of driving conditions and environments.

Assume that the weights of quarters are normally distributed with a mean of 5.67 g and a standard deviation 0.070 g. a vending machine will only accept coins weighing between 5.48 g and 5.82 g. what percentage of legal quarters will be rejected? round your answer to two decimal places.