The answer is A because you have to use the process of substitution
Since 15 workers did 8 hours of work, the total amount of work needed is 120 hours. Half of this job would be 60 hours. Then divide this amount by the 5 workers doing the job. This would make the job 12 hours
The full answer would be 83.454 but you can just say 83 pounds. Both are right
In order to find this you need to find a common denominator. 2/3 and 3/4 common denominator would be 12 and so what you do to the bottom you must do to the top. 2x4 is 8 and 3x3 is 9. that would make 8/12 and 9/12. 8 plus nine is 17 and 12 stays there so the answer is 17/12 which equals 1 and 5/10.