Answer:
$23
Step-by-step explanation:
You lose $14 in wages and it costs you an additional $9 to get into the fair. The cost to you of trading team practice for the fair is $14 +9 = $23.
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You can see this cost if you compare your net worth after your payment for going to team practice, versus your net worth after admission to the fair. In the first case it is ...
base-value + $14
In the latter case, it is
base-value - $9
The difference of these is
(base-value -$9) -(base-value +$14) = -$9 -14 = -$23
Skipping practice effectively reduces your net worth by $23 from what it would have been had you not skipped practice. That is your cost of going to the fair.