1 man can finish the work in (8 x 12) = 96 days
1 woman can finish the work in (4 x 48) = 192 days
1 child can finish the work in (10 x 24) = 240 days
1 man's 1 day's work = 1/96
1 women's 1 day's work = 1/192
1 child's 1 day's work = 1/240
(10 men + 4 women + 10 children)'s 1 day's work = (10/96 + 4/192 + 10/240)
= (5/48 + 1/48 + 1/24)
= (5 + 1 + 2)/48)
= 8/48 = 1/6
Hence, they will finish the work in 6 days.