A is able to complete a task in 15 days, while B takes 20 days to finish the same task. If they collaborate and work together for 4 days, what fraction of the work will still remain?A1/4B7/15C8/15D11/15Answer: C. 8/15 Read Explanation: Work rates per day:A’s rate =(115) ( \frac{1}{15} )(151)B’s rate = (120)( \frac{1}{20} )(201)Combined rate115+120=4+360=760\frac{1}{15} + \frac{1}{20} = \frac{4 + 3}{60} = \frac{7}{60}151+201=604+3=607Work done in 4 days4×760=2860=7154 \times \frac{7}{60} = \frac{28}{60} = \frac{7}{15}4×607=6028=157Work remaining1−715=8151 - \frac{7}{15} = \frac{8}{15}1−157=158 Read more in App