Question

A bus makes a stop at 2:30,letting off 15 people and letting on 9.The bus makes another stop ten minutes later to let off 4 more people.How does the number of people on the bus after the second stop compare to the number of people on the bus before 2:30 stop?

Answer 1

Whatever the initial number of people in the bus was, we know that this number underwent the following transformations: after the first stop, we have

`x \to x-15 \to (x-15)+9 = x-6`

After the second stop, we have

`x-6 \to (x-6)-4 = x-10`

So, globally, there are 10 people less at the end.