How many different ways can a director select 4 actors from a group of 20 actors?

Find the number of liters in 12.8 gal of gasoline. round to the nearest hundredths

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax

The given diagram shows the parts of a right triangle with an altitude to the hypotenuse. using the two given  measures, find the other four.