Try this solution:
rule: Distance=speed * time, where Distance=10216 (mi); t=8 (h) and speed=slower_jet + faster_jet (mi/h);
note, that faster_jet=slower_jet+65 (mi/h). Using these:
(slower_jet+65)*8=10216;
slower_jet=(10216-520)/16;
slower_jet=606 (mi/h);
faster_jet=606+65=671 (mi/h).
answer: 606 & 671
