The answer to the equation is x < 2.
For this case we have that the area of a circle is given by:

Where:
r: It is the radius of the circle
By clearing the radio we have:

We take the positive value:

The diameter is twice the radius:

Answer:

Split
into two component segments,
and
, parameterized by


respectively, with
, where
.
We have


where 
so the line integral becomes



It would take only one full bus to carry only girls.