Carla has $90. She makes $6 per day walking a neighbor's dog for half an hour, but she spends $7.50 per day on lunch. What is the fewest number of days for which Carla will have less than $30? Solve this inequality to find out. 90 + 6x - 7.5x < 30 (hint: combine like terms first)

A- 30
B- 41
C- 60
D- 90