if the 7th grade students at willow middle school have a class picnic each school year .this year 90% of the students attended the picnic.by 5 pm ,36 students had left the picnic and 3/4 of the students who came to the picnic stayed at the picnic .What is the total number of 7th grade students at willow middle school this year
Let the number of students =S
0.90S -36 =0.75(0.90S), solve for S
Solve for S:
0.9 S - 36 = 0.675 S
Subtract 0.675 S from both sides:
(0.9 S - 0.675 S) - 36 = 0.675 S - 0.675 S
0.9 S - 0.675 S = 0.225 S:
0.225 S - 36 = 0.675 S - 0.675 S
0.675 S - 0.675 S = 0:
0.225 S - 36 = 0
Add 36 to both sides:
0.225 S + (36 - 36) = 36
36 - 36 = 0:
0.225 S = 36
Divide both sides of 0.225 S = 36 by 0.225:
(0.225 S)/0.225 = 36/0.225
0.225/0.225 = 1:
S = 36/0.225
36/0.225 = 160.:
Answer: |S = 160. Number of students.
