KAlgebra/Credit payment

Function , which calculate the monthly interest rate by given yearly interest rate.

x-yearly given interest rate

f:= x-> x/12

Function , which calculate the whole sum you have to return to the bank

x- the sum you get from the bank

y- the monthly interest rate

z- how many month you have to pay the credit

c:=(x,y,z)-> x*(1+z*y/100)