Step-by-step explanation:
I guess, "you" and "I" are working with the same efficiency and work rate.
and with the typos in it, it is not clear, if I understood the problem and the given data properly.
but based on what I understood :
so, 3.6 customers in 0.5 hours.
7.5 hours × 2 = 15 times 0.5 hours.
15 × 3.6 = 54 customers.
so, with the same work rate as you, I helped 54 customers in 7.5 hours.
