Answer:
6 shirts
Explanation:
We need to subtract initial set time from 6.4
So,
6.4 - 4 = 2.4 minutes for batch of shirt
Each shirt takes 0.4 minutes and we have 2.4 minutes. Thus number of shirts is:
2.4 / 0.4 = 6 shirts
We have taken 4 minutes as initial time for any number of shirts.