En una tienda venden 10 tipos de helados, si un joven quiere comprar 4 helados, cuantas combinaciones de helados puede hacer?

Pls! does anybody know a shortcut for answering these types of questions in the future?

How many kilometers are equal to 5 miles? use 1 mile ≈ 1.61 kilometers. !

Olivia is using 160 quilt squares to make a red, yellow, and blue quilt if 25% of the quilt are red and 30% are yellow how many quilt squares are blue