Machine one will sew 1 shirt while machine four will sew 5 shirts at the same time, from the ratio given, machine four is the fastst.

Machine 4 can sew one shirt in 2 hours=> 5 shirts in 10 hrs.

Therefore, machines 1 will take 10 hrs for 1 shirt, machine 2 will take 10/2 hrs for 1 shirt, machine 3 will take 10/3 hrs for 1 shirt.

when all 3 machines are working together for 1 hr will produce = 1/10 + 2/10 + 3/10 = 3/5 shirts.

Therefore, it will take 5 hours to sew 3 shirts.

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To find what you seek in the road of life, the best proverb of all is that which says:

"Leave no stone unturned."

-Edward Bulwer Lytton