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 p.m., 36 students had left the picnic, and 34 of the students who came to the picnic were still at the picnic?
Using the numbers given, 36 students left and 34 students remained, we have 70 students are 90% of the entire student body.
0.9x = 36 + 34 = 70
x = 70 / 0.9 = 77.77777 students
It's impossible for part of a student to exist, so the 34 students who remained are only part of those who remained.
If there are 78 students at the school, 0.9 * 78 = 70.2 students attended the picnic.
If there are 79 students at the school, 0.9 * 79 = 71.1 students attended the picnic
Finally, if there are 80 students at the school, 0.9 * 80 = 72 students attended the picnic.
Apparently, 36 students left the picnic and 36 students remained.