question

i got a question on job costing where i understood everything apart from a sentence which is making me confused

it say 110 Direct labour hrs were worked in Department A at a basic wage of $4/hr. 30 of these hrs were classified as overtime at a premium of 50%.

upto this i’m clear

further it says all overtime worked in Department A in the month is as a result of the request of a customer for early completion of another job that had originally been scheduled for completion in the month following.
total labour hrs working in Dept. A during the month 2800

What does this mean.by what amount should i charge overtime premium as direct cost to this particular job.Is it only 30 hrs as specified or as the sentence is saying all overtime done is at the request of the customer.I couldn’t understand that. Further how can we calculate what is the total no of overtime hrs worked in that total 2800 hrs.

No solution is given,its an exercise question