A polygon with 7 sides is a heptagon.
Given:
number of sides = n = 7
The sum of interior angles in a polygon is given by;

Therefore, the sum of the interior angles of a polygon with 7 sides is 900 degrees.
For this case, the first thing we must do is define variables.
We have then:
n: number of cans that each student must bring
We know that:
The teacher will bring 5 cans
There are 20 students in the class
At least 105 cans must be brought, but no more than 205 cans
Therefore the inequation of the problem is given by:
Answer:
105 <u><</u> 20n + 5 <u><</u> 205
the possible numbers n of cans that each student should bring in is:
105 <u><</u> 20n + 5 <u><</u> 205
30 notebooks, 300 notebooks divided by 10 = 30