Answer:
10
Step-by-step explanation:
one interior angle in a pentagon is 108^o.
5 interior angles are 540^o.
If we add 12+7+16+9+10, we get 54x=540^o
That means x=10
Answer:

Step-by-step explanation:
Let's solve this problem step-by-step. The library had 1,500 books in 2011. The ratio of books in 2011 and in 2012 is 1:2. Therefore, let the number of books in 2012 be
.
We have the following proportion:

Therefore, there were 3,000 books in 2012. The ratio of books in 2012 and in 2013 is 2:5. Let the number of books in 2013 be
.
We have:

Therefore, there were 7,500 books in 2013.

and surely you know how much that is.
For this case we have a quadratic equation of the form:

What we must keep in mind to know which direction opens the parabola, is the value of a.
We have two options:
If a <0 the parabola opens down
If a> 0 the parabola opens up
We have the following equation:

We observed that:

Therefore, the parable opens up.
Answer:
the direction that this parabola opens is:
Upwards