15x 1
————— = —————
20(20 x)2
15x 1
————— = —————
400-20x 2
(15x) (2) = (400-20x) (1) (using cross multiplication)
30x = 400-20x
50x = 400
x = 8
Therefore, eight people should be arranged to process the screws, so that each screw can be equipped with two nuts after processing.