You've parenthesis in the wrong place

(vehicle.v_mileage-MIN(a_startmile))/6.5 as average

>I am trying to get an average from following sql statement but it returns wrong number:
>
>v_mileage = 50
>min(a_startmile) = 30
>v_mileage-(min(a_startmile) is equal to 20
>
>
>

(vehicle.v_mileage-(MIN(a_startmile))/6.5) as average

>
>
>gives me

45.3846

which is wrong.
>
>Is there a trick to get an average in an sql statement?