Since you subtract 6 and you have to find the sixth term, you can do: -6×5=-30 ( negative shows you're subtracting and since 75 is the first term, then you have to find the difference of the input/term 6-1, the sixth term minus the first) 75-30=45 You can check by actually continuing the pattern. 75,69,63,57,51,45,39......
There is a formula for that; Total time = (Worker 1 * Worker 2) / (Worker 1 + Worker 2) Total time = (80 * 120) / (80 + 120) Total time = 9,600 / 200 Total time = 48 minutes
