Please help quick and explain the answer 3^a / 9

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.

Find the solution of this system of equation -7x+y=-20 9x-3y=36

Iwill give you ! what is the measure of ∠v ?