This is the question and the solution, can you please help me with what is circled in red. how did we get these numbers. please be detailed in your explanation in how you got the red.

A toy factory is planning to make an additional item which would be processed sequentially in four different departments. The company is proposing to produce 600,000 units per year, working 250 days per year. The following estimates of times are made by an industrial engineer. Department 2. 3 4 Average Processing Time (sec/part) 8 13 10 50 Avg. Maintenance Time (min) 20 30 20 15 Avg. Daily Setup Time (min) 20 15 30 20 Avg. Bookkeeping Time (min) 10 8 12 5 Machine Adjust. Time (min) 15 10 15 15 Defective Items (%) 5 6 4 4 78 a) Determine the number of units that must be produced each day in each department if all the defective units are scrapped. Determine the number of machines needed in each department to meet the production goals. b) Solution: a) The total number of output from the factory per day is 600,000'units/250 days, or 2400 units per day In order to get this quantity out it is necessary to input more in order to account for the number of defectives. determine the required inputs, it 1s necessary work backwards from the known output. This gives the following required production per department: to Department 4: Department 3: Department 2: Department 1: Input = /2400/.96 Input 2500/.96 Input 2605/.94 Input 2772/.95 2500 units 2605 units 2772 units 2918 units b) it To determine the number of machines required, is necessary to divide the total amount of time required to produce the required quota/department by the total processing time per day available. Daily working time = 480 40 - 20 = 420 min/day : Dept;Inputi Proc. i min 1 day machine 1/mci H/time 1 Work Main. Setup Bkkp. Adj. i required + - + 1 2918 x 0.13 V ( 420 20 20 15 ) = 1.16 (2) 2 12772 x 0.21 V ( 420 20 15 30 20) = 1.79 (2); 3 | 2605 x 0.16 / ( 420 10 8 12 5) = 1.12 (2); ! 4 2500 x 0.83 / ( 420 15 10 15 15 ) = 5.70 (6) + 30