According to Grammarly and other sources, (such as school lol), a concrete noun is a noun that can be identified through one of the five senses (taste, touch, sight, hearing, or smell). Consider the example below: the noun phone is a concrete noun: you can touch it, see it, hear it, and maybe even smell it or taste it.
First, subtract the 10.00 from 120.50. = 110.50 Second, add the amount of hours she has worked. 4+3+6=13 hours. Third, take 110.50 and divide it by the amount of hours. Your answer is $8.50 an hour.