HElp plz 30 pointss!!

Find the height of a square pyramid that has the volume of 32 ft.³ and a base lengthof 4 feet

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5

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