Answer:
Easton entered in 25 shows last year.
Explanation:
Given that Easton won best in show in 60% of the shows I have entered, to determine how many show was Easton entered if he won best in show 15 times last year, the following calculation must be performed: 
 
60 = 15 
100 = X 
(100 x 15) / 60 = X 
1,500 / 60 = X 
25 = X 
 
Therefore, Easton entered in 25 shows last year.