Consider a laundry service that has 3 steps to its process.

Step 1 is Washing, Step 2 is Drying, Step 3 is Ironing & Step 4 is Packaging.

Step 1 Washing is a batch operation, with a batch size of 50 pieces of clothing, variable time of 15 seconds per piece and a fixed time of 20 minutes. There is one washing machine.

Step 2 Drying is also a batch operation, with a batch size of 40 pieces of clothing, variable time of 20 seconds per piece, and a fixed time of 60 minutes. There is one drying machine.

Step 3 is a manual operation where a team of 2 workers iron the clothes; each worker takes on average 3 minutes to iron a piece of clothing.

Step 4 is again a manual operation, where only one worker packages the clothes in an average of 2 minutes per piece; only 50% of the clothes need packaging.

Answer the next several questions based on the data above.

The capacity at washing in pieces of clothing per hour is (pick the closest integer):

a 62 per hour

b 72 per hour

c 92 per hour

d 102 per hour