To represent the amount of money that Harun and Breelyn have leftover after buying bags of candy, we can start with the total amount of money they have, which is $30. Each bag of candy they buy costs $3, so the combined cost for Harun and Breelyn can be expressed as \(3H + 3B\) (where \(H\) is the number of bags Harun buys, and \(B\) is the number of bags Breelyn buys).
To find the amount of money left over after purchasing the candy, you would subtract the total cost from the total money they had:
\[ \text{Amount leftover} = 30 - (3H + 3B) \]
Simplifying this expression results in:
\[ 30 - 3H - 3B \]
Thus, the correct expression to represent the amount of money they have leftover is:
30 - 3H - 3B