7 rollercoasters because 4 shows plus 3 more rolercoasters equal 7 and 4 shows .It takes 5 minutes to ride on the rollercoaster plus the estimated 30 minute wait equals 35 and 35*7=245 and it takes 25 minutes to watch show and 25*4=100 and 245+100=345 so he can ride 7 rollerecoasters and 4 shows in 345 minutes.
The last resort because you have no more options