Rael bought some notebooks at $3 each. He later sold them to his customers at $8 each. For customers who bought two notebooks were given another notebook for free. The customers bought either one or two notebooks. Rael gave away 110 free notebooks and collected a total of $1320 more than what he had paid for. How many customers bought just one notebook?
110 free so 110 people bought 2 and got 3 for $16
3 * 110 = 330 notebooks and 110 * 16 = $1760 in for batches of 3
x people bought one so 8 x dollars in for the one notebookers
total income = 8 x +1760
so
8 x + 1760 = 3 ( 330 + x) + 1320
5 x = 550
x = 110
check my arithmetic, did that fast