There are 7 people on the bus after the first stop. There are 7 + 5 - 3 = 9 people on the bus after the second stop. There are 9 + 4 - 2 = 11 people on the bus after the third stop. 11 passengers are now on the bus.
This justifies what answer for what question? Q & A:
The bus started its route. At its first stop, 7 people got on. At the second stop, 3 people got off, and 5 people got on. At the third stop, 2 people got off, and 4 people got on. How many passengers are now on the bus?
11