According to the known conditions, the number of people getting off the bus should be greater than 0, and the remaining number should be greater than or equal to 0.

Then 5a-4-(7-2a) ≥ 0

7-2a>0

The solution is 1 1/7 ≤ A < 3.5.

The integer solution of a is 2 or 3.

When a=2, 5a-4 = 6.

When a=3, 5a-4 = 1 1.