Since the problem asks how many students who like mathematics, only that the existing diagram to calculate what the problem, by taking n = 140 (M) to minus-three best known number.
The prosecution asked for the number of students who like math alone. This diagram is sufficient to calculate what the prosecution asked by n (M) = 140 to minus three sections and then note the number.
Since the word ask a number of students like mathematics. The plan sufficient to calculate what problems existing questions by using n (M) = 140 to minus three the note number.