Then I hit this one:
19. A commercial jet can fly from San Francisco to Dallas in 3 h. A private jet can make the same trip in 3 1/2 h. If the two planes leave San Francisco at noon, after how many hours is the private jet twice as far from Dallas as the commercial jet? (page 246)I couldn't do it, and I didn't enjoy not being able to do it.
I'm not even going to look at #20.