Ugh i’ve been stuck on this since yesterday

Marla bought a book for $12.95, a binder for $3.49, and a backpack for $44.99. the sales tax rate is 6%. find the amount of tax and the total she paid for these items

The pyramid shown has a square base that is 24 centimeters on each side. the slant height is 16 centimeters. what is the lateral surface area?

Ms.lopez has 4 liters of chemicals that she is going to pour into beakers. each beaker will have 1/4 of a liter of chemicals, how many beakers can ms.lopez fill? draw a model to support your work. (it's ok if you dont)