a teacher brought to class a pack of notebooks. if her gives his students 5 notebooks to each, he will have 7 notebooks left. if he tries to give each student 7 notebooks, he will be 5 notebooks short. how many students are there in the class?

There are six students in his class

6 students

Step-by-step explanation:

Let the number of notebooks be $x$ and the number of students be $y.$

If there are 5 notebooks per student, we have:

$x-5y=7$

Simliairly, we have 7 notebooks per person, which is:

$x-7y=-5$

Then, using system of equations, we can add multiply the first equation by $-1$ and then add.

We would have:

$-1(x-7y=-5)=-x+7y=5$

Then, adding gives us:

$2y=12$

$y=6$

i belive those are the ones that are under 90 degreese.

2x^2+5x+17

your welcome. : )