Answer:
6 swimmers in the first heat can be arranged in 1716 different ways.
Step-by-step explanation:
A swim meet has 13 contestants signed up. To calculate the arrangement of first 6 swimmers in first heat we will use combinations because order doesn't matter.
So to select 6 swimmers out of 13 contestants number of different ways
= 
= 
= 
= 
= 
= 1716
Therefore, 6 swimmers in the first heat can be arranged in 1716 different ways.
14 over 4509 would be an equvilent fraction
6:15 is in ratio form..... If you mean fraction form, a ratio is equivalent to a fraction, so the answer is 6/15
5u > 64 - 14
5u > 50
u > 10