In the question it is given that,
The students at Midtown Middle school sold flowers as a fundraiser in September and October. In October, they charged $1.50 for each flower
And the October price was a 20% increase of the September price.
Let the price of the flower in October be $x
So we have

So the price of the flower in Septembet is $1.25 .
The given expression is:
(x^3 * y^4) / (3y^4)
We can notice that the term y^4 is a common term found in both the numerator and the denominator of the given expression, therefore, we can cancel this term from the both numerator and denominator (as if you divided both numerator and denominator by y^4).
Doing this, we will have the simplified form of the expression as follows:
(x^3) / (3)
The pentagon does not belong because it has 5 sides while the other 3 shapes have only 4 sides.
5ml=1 teaspoon
2.5ml=1/2 teaspoon
so 2.5ml is equal to half teaspoon