Function p and q examples

Astore ordered 750 candles a total wholesale cost of $7910.20. the soy candles cosy $12.17 each and thespecialty candles cost $9.58each. how many of each were bought?

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?

For a function f(x), a) if f(7) = 22 then f^-1(22) = b) f^-1(f(c)) =