M and N, working in tandem, can successfully attain the sales target within a span of 15 days. Now, if N's efficiency is _______ percent less than that of M, what is the duration _______ in days that N, working alone, requires to accomplish the sales target? Which set of values from the options provided will correctly complete the statement to render it accurate?
i)  25, 35 ii) 50, 45 ii) 40, 40

ATQ, Let the efficiency of M be ‘20m’ units/day For i: Efficiency of N = 20m × 0.75 = ‘15m’ units/day Total amount of work = (20m + 15m) × 15 = ‘525m’ units Time taken by N alone to complete the whole work = 525m ÷ 15m = 35 days Therefore, (i) is true. For ii: Efficiency of N = 20m × 0.50 = ‘10m’ units/day Total amount of work = (20m + 10m) × 15 = ‘450m’ units Time taken by N alone to complete the whole work = 450m ÷ 10m = 45 days Therefore, (ii) is true. For iii: Efficiency of N = 20m × 0.60 = ‘12m’ units/day Total amount of work = (20m + 12m) × 15 = ‘480m’ units Time taken by N alone to complete the whole work = 480m ÷ 12m = 40 days Therefore, (iii) is true.