Can someone me with this or just give me the answer

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?

Dots sells a total of 279 t-shirts ($2) and shorts ($4). in april total sales were $670. how many t-shirts and shorts did dots sell?

Which graph represents the same relation is the sa which graph represents the same relation as the set {(-3-2)}