Thirty percent of all the students in a school are in a play. All students except for 140 are In the play.

Let x = the total number of students, and p = number of students in the play.

If 30 percent of students are in the play:

.3x = p

If All except for 140 are in the play:

x - 140 = p

Now we have 2 equations, so use substitution to solve for x:

x - 140 = .3x

x - .3x = 140

.7x = 140

x = 140 / .7 = 200

Now that we know x, solve for p:

200 - 140 = p

60 = p

There are 200 students total, and 60 in the play.