No, it is an exacta which means you have to pick the horses that come in 1st and 2nd...
So... he picks the 4 horse to come in first and is picking the 3,7,9 to come in second. 3 bets total
FYI, anytime you see a / that distinguishes the a horse from being picked to come in 1st or 2nd. For example, 4/3-7-9 means 4 to come in 1st, 3-7-9 to come in 2nd.
If it read 4/3-7-9/3-7-9 that would be a trifecta, 4 for first, 3-7-9 for second, 3-7-9 for third.
Hope that helps...good luck, I like the 4/3-7-9 exacta myself.