What is the total number of outcomes if you there are three sizes of milk shakes (S, M. L) and five flavors of ice cream (Vanilla, Chocolate, Strawberry, Mint, Lemon)

5 small milkshake outcomes

5 medium milkshake outcomes

and

5 large milkshake outcomes

since there are only 5 flavors you can only make 5 different milkshakes unless you want to mix the flavors to make

5+10 = 15 so you could make 15 that mixing each ice cream with each other and then mixing all of them.