Geometry, surface area and volume

Ricky takes out a $31,800 student loan to pay his expenses while he is in college. after graduation, he will begin making payments of $190.66 per month for the next 30 years to pay off the loan. how much more will ricky end up paying for the loan than the original value of $31,800? ricky will end up paying $ more than he borrowed to pay off the loan.

Is the number 128.439 a rational number

Given the functions, f(x) = 2x^2 - 1 and g(x) = 5x, find f(g(x)) and g(f(