Chapter 7 - Section 7.6 - Proportions and Problem Solving with Rational Equations - Exercise Set - Page 539: 35

20 mph of the wind

distance = rate * time with wind: 400 = (230+x)*t against wind: 336 = (230-x)*t $400=(230+x)*t$ $400/(230+x)=(230+x)*t/(230+x)$ $400/(230+x)=t$ $336 = (230-x)*t$ $336/(230-x) = (230-x)*t/(230-x)$ $336/(230-x) =t$ $400/(230+x) = 336/(230-x)$ $336*(230+x) = 400*(230-x)$ $77280 +336x = 92000 - 400x$ $736x = 14720$ $736x/736 = 14720/736$ $x=20$