We know, 3 feet = 1 yard.
We have to convert feet to yards to calculate the ratio so that the final answer doesn't have any unit.
Therefore, 21 feet =
= 7 yards
Thus, the ratio

The fraction
is already in its simplest form.
Therefore, the given ratio as a fraction in the simplest form without any units is 
Jim is ranked third best in his class of 50 students.
Answer:
use Pythagoras theorem formula
=
+ 
Step-by-step explanation:
=
+ 
= 576 + 324
= 900
C = 
C = 30
Does that make sense? :|