Let the total work be LCM(10, 12, 20) = 60 units
=> Efficiency of A = 60/10 = 6 units / day
=> Efficiency of B = 60/12 = 5 units / day
=> Efficiency of C = 60/20 = 3 units / day
Since the number of working days are different for each person, the share of each will be calculated in the ratio of the units of work done.
Now, A works for 2 days and B works for 3 days.
=> Work done by A = 2 x 6 = 12 units
=> Work done by B = 3 x 5 = 15 units
=> Work done by C = 60 – 12 – 15 = 33 units
Therefore, ratio of work done = 12:15:33 = 4:5:11
So, A’s share = (4/20) x 2,00,000 = Rs 40,000
B’s share = (5/20) x 2,00,000 = Rs 50,000
C’s share = (11/20) x 2,00,000 = Rs 1,10,000
Therefore, difference of the highest and lowest share = Rs 1,10,000 – 40,000 = Rs 70,000