Answer:
6 men are ill.
Explanation:
the work of 30 men in 40 hours is the product
30×40
an unknown number of men (x) is sick, and now the remaining workers do the same work in 50 hours
(30-x)×50
so,
30×40 = (30-x)×50
1200 = 1500 - 50x
-300 = -50x
x = 6