To start this question, put all of the terms in the same unit. Yards and feet aren’t equivalent, but a simple multiplication can put them in the same unit (1 yard = 3 feet).
60 feet in 1.5 hours vs. 90 feet in 2.5 hours
Now, put the distance travelled by each in the same amount of time. You can reduce these to one hour each, or you can multiply both by a common denominator to save some fraction work (the first CD I can calculate is 30 hours, so multiply each fraction by the necessary number to bring the denominator to 30).
(60 feet/1.5 hours) x 15 = 900 ft/30 hours
(90 feet/2.5 hours) x 12 = 1080 ft/30 hours
1080 feet in 30 hours is greater than 900 feet in 30 hours, so 90 feet in 2.5 hours is faster than 20 yards in 1.5 hours.
Hope this helps!