To figure out which airline provides more reliable service, we need to figure out what ABC Airlines's delays are in percents.
To get that, we need to reduce 18/126 by 2.
When we reduce both the numerator and the denominator we get 9/63.
Now, we cannot reduce that again, without getting a decimal for the numerator/denominator.
So, now that we know that the fraction is 9/63, we divide it, and we get :
0.142857
Changing that into a percent, we get 14%.
14% is the percent that ABC Airlines has delays.
DEF Airlines has delays of 13% in recent flights.
So, from that, we can conclude that DEF gives more reliable service.