When you tap on your truck orders board, the amount of coins that will be received after completing an order are highlighted in pink. This amount has already been totalled to the double amount you will receive altogether.
The event bonus is added together with the possible mastery bonuses, so that you should see first the regular reward being added, followed by one bonus sum that includes both the event and the mastery bonus.
For example, if you complete an order worth 300 coins and 100 experience points, it will first animate the original reward of 150 coins. Then, another animation will show the bonus coins flying up, which would be at least another 150 coins – or possibly more, if some mastery bonuses are rewarded, too.