Please help with this, need the answer ASAP, please explain your reasoning for both of these!

Isee the amount was $90.00 then reduced to $75.00 , what is the percent ?

What is the solution of the systems of equations? y=2/3x+3 x=-2

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.