Explanation:

Correct Option is 2 :9 days

4 men and 5 women 1 day earning = 8800/8 4 men and 5 women 1 day earning = 1100
7 men and 10 women 1 day earning = 10250/5
7 men and 10 women 1 day earning = 2050
let the men earning is x and women earning is y
4x + 5y = 1100
4x = 1100 - 5y
x = (1100 - 5y)/4
-- (1)
7x + 10y = 2050
7(11005y)/4+10y= 2050 (from 1)
(7700-35y)/4+ 10y= 2050
⇒(7700 - 35y + 40y)/4 = 2050
⇒ 7700+5y=2050 x 4
⇒ 7700 + 5y = 8200
5y= 8200-7700
⇒ 5y = 500
⇒y = 100
x=(100 - 5 x 100 )/4
x=150
One day earning of 8 men and 12 women is (8x150) + (12x100)
=>2400
then 21600 is the earning of  (21600/ 2400) days = 9 days.