He paid him : 24t + 15
for 3 hrs...
24(3) + 15 = 72 + 15 = $ 87
2.

(this is given in the first sentence)
3.

and

due to ...
7. ... the alternate interior angles theorem (which holds because

and

are parallel)
8. Because the above establishes that

, which means

, which in turn means

is a parallelogram.
Since h represents the height of the ball at any given time, t, let h = 25, such that the ball will be 25m high at t.
Now, we have 25 = 20t - 5t²
5t² - 20t + 25 = 0
t² - 4t + 5 = 0

Since the discriminant is less than zero, there are no solutions.
Hence, the ball will never be 25m high.
If it takes .1 hours to walk 2/6 miles, then it takes one hour to walk 20/6 miles.
20/6 miles = 3.33 miles
So that is 3.33 miles per hour.