Alejandro bought $3. 50 worth of pencils and erasers at the school store. Pencils cost $0. 50 apiece, and erasers cost $0. 75 apiece. Which equation written in standard form represents the number of pencils, p, and the number of erasers, e, that alejandro bought? 0. 75e = 3. 50 – 0. 50p 0. 50p + 0. 75e = 3. 50 3e = 14 – 2p 2p + 3e = 14.