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 2*x* + 1.5*y* for the first child and *x* + *y* for each of the remaining *n* – 1 children, so altogether she made:

2*x* + 1.5*y* + (*n* – 1)(*x* + *y*) =

(*n* + 1)*x* + (*n* + .5)*y* =

*n*(*x* + *y*) + *x* + .5*y*