7a/9bc divided by 21a/12b

Given the function f(x) = log base 4(x+8) , find the value of f^-1(2)

Find dy/dx using implicit differentiation ln(20+e^xy)=y

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.