Alex drove 80 miles from his house to pick his sister up from college. After spending only 10 minutes loading his sister's belongings, he immediately drove them back home.
The entire trip took 170 minutes. What was Alex's average driving speed in miles per
hour?

U pp

Step-by-step explanation:

Big pp

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.