The one with domain {8, 3, 1} and range {6, 2, 7, 9}(top-left)  is not a function because 3 is being mapped to two different values, 2 and 7. 
        
             
        
        
        
let's take admission fee= z
8z+11z=17.50+21.25
19z=38.75
z=38.25/19
z=2.4 (aprox)
Or In case of Kiara 17.50 amount paid in 8 rides
.so 1 ride=17.50/8
=2.1875
same In case of mia 
so 1 ride=21.25/11
=1.9318. 
but, they are not match so there is problem in your Questions.
 
        
             
        
        
        
The discount is 65%
sorry for the mistake
        
             
        
        
        
Answer:
He would weigh 78.9 kilograms. hope this helps.