Yes because precise means specific.
The existence proof of the empty set is an absolute gem
3 2/3 hours. Because if you do 2 3/4 times 1 1/3 you get 11/3 which simplifies into a mixed fraction of 3 2/3.
First you convert 20% into a decimal which is 0.2 and multiply that by 42 and you get 8.4, that's the discount. Then you subtract 8.4 from 42 and get $33.60 which is your answer. Hope this helps!!