The ladder is the hypotenuse of a 45 45 90 triangle.
The legs of a 45 45 90 triangle = hypotenuse / sqroot (2)
15 / 1.414 = 10.608
(Incidentally it is the "bottom" of the ladder that is 10.608 feet from the wall. The "top" of the ladder is touching the wall. LOL)
I don't know specifically what the sum and product of an equation is but
factor using quadratic formula
if you have an equation in ax^2+bx+c=0 then you can solve for x using

or

so input
a=1
b=7
c=2



=aprox -0.2984378812836



=aprox -6.7015621187165
They cross each other at (5,2)
(180 miles=7.5 hours, 20 miles=2.5/3=0.8333) 7.5+0.8333=8.3333 or 8h and 20 minutes.