Again
In 2003 you have to renovate the airplanes park , updating the fleet essentially, for both the airline companies: A and B
Now, A must fade out the first year way back ten year which is 1993 and its old airplanes are 10% of the total, that is 250 airplanes.
Same has to do airline company B: in 1993 it has 20% of the total aiplanes owned and this 20% must be fade out.
So for A the aiplanes go from 250 to 225: 250*0.9=225
For B is the same calculation: 450*0.8=360
On BOTH RESULTS you have to add a constant which is 10%, which is the percentage that BOTH companies must add to the fleet to update the same
For A 225*1.1=247
For B 360*1.1=396
So the combined number of the total airplanes for both A+B is = 644 for 2003
The same calculation must be done for the year 2004 to find A+B
I hope now is clear
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