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?
O 0.75e = 3.50 -0.50p
O 0.50p + 0.75e = 3.50
O 3e = 14 -2p
O 2p + 3e = 14