Question 293821
Let x be the number of students on the bus before the first stop.
Now, let's start adding/subtracting with each stop
{{{x -4 + 7 }}} after the first stop or {{{x+3}}}
{{{(x+3) - 2 }}} after the second stop or {{{x +1}}}
{{{(x+1) - 12 }}} after the third stop oss {{{x -11}}}

You also know that all students are off the bus after the final stop. So
{{{x-11 = 0}}}
{{{x = 11}}}

Check your answer