Holly used to get $2.00 per hour babysitting one child if it was awake and $1.50 per hour if it was asleep. Each additional child was another dollar per hour, awake or asleep. If she took care of n children for x hours before bedtime and y hours after bedtime, how much money did she earn? (The answer is a formula.)
Holly earned 2x + 1.5y for the first child and x + y for each of the remaining n – 1 children, so altogether she made:
2x + 1.5y + (n – 1)(x + y) =
(n + 1)x + (n + .5)y =
n(x + y) + x + .5y