Cindy and John, working together, can paint the deck in 2 hours. Working alone, John takes twice as long as Cindy. How long does it take Cindy to paint the deck alone?
1/C + 1/(2C) = 1/2, solve for C
C = 3 hours - Cindy working alone
3 x 2 = 6 hours -John working alone.
+36916 x = time for cindy alone
2x = John time alone
1/x + 1/2x = 1/2 mutiply both sides by x and 2x
2x + x = 1/2 (x)(2x)
3x = x^2
x^2 - 3x = 0
x(x-3) = 0 so x = 3 or 0 (throw out) x = cindy alone = 3 hours
