Hi!
We are given the information found in the picture below.
Note: The directions aren't correct, but the triangle works for this problem.
The "direct path" is the hypotenuse of this triangle.
To find this, we use the Pythagorean Theorem, where 
and 
are 2 legs of the triangle, and 
is the hypotenuse, aka the longest side of any triangle:
We know and and want
Therefore, is approximately 
The measure off DF is 11.
In a circle inscribed within a triangle, the distance from each vertex of the triangle to the two nearest touchpoints (points of tangency on the circle) are equal. Since SD=4, DT=4 as well. Since UF=7, then FT=7.
DF=DT+TF=4+7=11.
21.12 is 25.6% of 82.5. I hope this helps. :)
#1) x-8= -12
#2) 15+k= 2
#3) x/-7= -20
#4) (5/8)(x)= -20
The / in #2 means to divide and the ( ) mean to multiply
