Let T be the total number of seats before the additional number were added
And let R be the revenue collected before the additonal seats were added
So we have this system
.75T(40) + .25T(75) = R (1)
.75T(40) + (1460 - .75T)(75) = R + 21900 (2)
Substituting (1) into (2), we have
.75T(40) + (1460 - .75T)(75) = .75T(40) + .25T(75) + 21900 simplify
109500 - 56.25T = 18.75T + 21900
75T = 87600
T = 1168
And after the seats were added, the number of VIP seats = (1460 - .75*1168) = 584
And the % of VIP seats after the seats were added = 584/1460 = 40%