Answer: 7.5 hours
Step-by-step explanation:
rate of first crew is 8 hours
jobe done by first crew in 2 hours is 2(1/8)= 2/8= 1/4
job left is 1-1/4= 3/4
rate of second crew 10 hours
time need to finish...
10(3/4)= 10(7.5)= 7.5
7 hours 30 minutes to finish