At a school, 106students play at least one sport. this is 40% of the students at the school. how many students are at the school?

There are several information's of immense importance already given in the question. It is important to minutely check them before going for solving the problem.
Let us assume the number of students at the school = x
the total number of students playing at least one sports = 106
Percentage of students playing at least one sports = 40%
Then
40% * x = 106
(40/100) * x = 106
4x/10 = 106
4x = 106 * 10
4x = 1060
x = 1060/4
   = 265
So there are 265 students at the school.

Def is a scalene triangle

The variables should add up to equal 1