Does it pay to study for an exam the number of hours studied X is compared to the exam grade received y

On the april 3 billing date, michaelle chappell had a balance due of $ 1495.39 on her credit card. from april 3 through may 2, michaelle charged an additional $ 305.34 and made a payment of $ 800.a) find the finance charge on may 3, using the previous balance method. assume that the interest rate is 1.8 % per month.b) find the new balance on may 3.

For f(x)=2x+1 and g(x)= x^2 -7, find (f•g)(x)

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.