90:2 1/2
90/3 : (2 1/2)/3
30 : (2 1/2)/3
30 : (5/2)/(3/1)
30 : 5/2*1/3
30 : 5/6
30km in 50 mins
90 : 2 1/2
90/(2 1/2) : (2 1/2) / (2 1/2)
90/(2 1/2) : 1
(90/1)/(5/2) : 1
(90/1)*(2/5) : 1
180/5 :1
36:1
Multiply each side by 2:
72:2
72 km in 2 hours
Hope this helps :)
