Directions. Work each problem and select your answer. As soon as you choose, the full explanation appears below the question — read it before moving on, even if you got it right. Use the Eliminate feature if you want to cross out choices as you work. The floating Calculator button opens a Desmos graphing calculator you can drag anywhere on screen. When you are done, use Print / PDF for a clean, ink-light black-and-white copy with a full answer key on the last page.