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

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Kevin F. | Computer Programming and Mathematics TutorComputer Programming and Mathematics Tut...

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.

30% are in the play

70% are not in the play

140 are not in the play

140 is 70% of total # of students(call this n)

140=70%*n

140=0.7n

1400=7n

1400/7=n

200=n

Derek W. | Math and Science Tutor in Cabot AreaMath and Science Tutor in Cabot Area

What you know: 30% of all students in play & 140 students not in the play

What you need to know: # of students in school

Formulas: Total Students in School x % in play = # students in play

Students in play + Students not in play = Total Students in School

If you merge the two formulas you get: Total Students in School = (Total Students x % in play) + students not in play.

Plug in the numbers: Total Students = (Total Students x 30%) + 140 -or- x=.30x+140

Solve for x:

Subtract 0.30x from both sides: x-.3x = 140 -or- .7x = 140

Divide both sides by .7: 0.7x / 0.7 = 140 / 0.7

You get x = 200. So there are 200 students in the school

Hi Travina;

30%=0.30

x=total number of students

(0.30)x=x-140

Let's subtract x from both sides...

-x+(0.30)x=-140

-(0.70x)=-140

Let's divide both sides by -0.70

-(0.70x)/(-0.70)=-140/(-0.70)

x=200

30% of 200=0.30(200)=60 students in play

140 are exceptions who are not in play.

60+140=200

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