Let K and T be the speeds of Kirk and Thor respectively.
Note the standard definition that d=vt, distance equals velocity times time.
t=d/v
For Kirk, t=525/(T+5)
For Thor, t=490/T
Since we are told that they have traveled the same amount of time we can say t=t which leaves us:
525/(T+5)=490/T multiply both sides by T
525T/(T+5)=490 multiply both sides by T+5
525T=490T+2450 subtract 490T from both sides
35T=2450 divide both sides by 35
T=70
So Thor's average speed is 70kph, since K=T+5
K=75kph
So Kirk's average speed is 75kph
