A stationery shop orders a batch of pens from a factory.The factory could make the batch of pens in 20 days using 12 machines. Due to a fault, only 3 machines were used for the first 8 days. All 12 machines were used from day 9 onwards. Work out the total number of days taken to make the batch of pens.

Final answer: To complete the work, 8 days were initially used with only 3 machines, and then another 18 days were required after the remaining machines were activated, for a total of 26 days. Explanation: The subject of this problem is Work Rate. Work rate (also known as work speed) problems are common in basic algebra. In this case, the problem is dealing with multiple machines operating at the same speed to produce a batch of pens. First, we need to find out how much work each machine does in one day. From the problem we know that 12 machines can finish the work in 20 days, so this means one machine would take 12*20 = 240 days to finish the work alone. This means every day, a machine completes 1/240 of the work. For the first 8 days, only 3 machines were active. This means they completed 3/240*8 = 1/10 of the work. Then, the rest of the 12 machines are turned on, each completing 1/240 of the work every day. So to complete the rest of the work (1 - 1/10 = 9/10), it would take (9/10) / (12/240) = 18 days. So, adding the two periods together, the total time taken to make the batch of pens is 8 + 18 = 26 days. Learn more about Work Rate here: brainly.com/question/32067973 #SPJ11