Someone help me with this please, I really need help, and it's due tmrw...PLEASE

Satchi found a used bookstore that sells pre-owned dvds and cds. dvds cost $9 each, and cds cost $7 each. satchi can spend no more than $45.

How many different three-digit numbers can be formed using the digits 1 comma 2 comma 9 comma 6 comma 4 comma 3 comma and 8 without repetition? for example, 664 is not allowed.

The moats separating people from the animals are 5 m wide for lions and 4 m wide for the elephants. if the lion’s moat is 4 m deep, how deep should the elephants’ moat be?