D is the answer
%ge of Flights delayed: 43+17+12+3=75
Therefore,75% were delayed.
From the question,
.75(Total Number of flights)=1200
Total Number of flights=1600
Flights on time(X)
= 100-(%Delayed flights)
Therefore, flights that departed on time are
510 on my first GMAT. 610 on second GMAT.!
The struggle continues.