Chapter 7 - Section 7.6 - Proportions and Problem Solving with Rational Equations - Exercise Set - Page 539: 36

1 hour

downstream: 9 = (x+6)*t upstream: 3 = (x-6)*t $9=(x+6)*t$ $3 = (x-6)*t$ $9=(x+6)*t$ $9/(x+6)=(x+6)*t/(x+6)$ $9/(x+6)=t$ $3 = (x-6)*t$ $3/(x-6) = (x-6)*t/(x-6)$ $3/(x-6) = t$ $9/(x+6)=3/(x-6)$ $3(x+6) = 9(x-6)$ $3x+18 = 9x-54$ $3x+72= 9x$ $72=6x$ $6x/6 =72/6$ $x=12$ $9=(x+6)*t$ $9=(12+6)*t$ $9 = 18*t$ $9/18 = 18*t/18$ $.5=t$ $3=(x-6)*.5$ $3=(12-6)*.5$ $3=6*.5$ $3=3$ $.5+.5=1$