The multiple of 5 is 40.
7 has 28 multiples.
These three numbers are repeated twice, so we have to subtract them once.
The common multiple of 3 and 5 is 13.
3 and 7 have nine common multiples.
5 and 7 have five common multiples.
The common multiple of three numbers, 3 5 7, is repeated three times, so it will be subtracted twice.
Then the students facing the teacher are: 200-66-40-28+13+9+5+2 = 95.