If the domain of the square root function f(x) is x< equal to 7, Which statement MUST be true?

At the beginning of 1974/75,2 years a man invested #2000 in a bank at 12.5% compound interest, if it degree #650 at the end of each two years to pay his son's school fees, after payment of interest to pay his son's school fees, how much did he have left at the beginning of the 1978/79 school year?

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?

If value of cos330° is √3/2 then find tan165°.