Question

Following a severe​ snowstorm, Ken and Bettina Reeves must clear their driveway and sidewalk. Ken can clear the snow by himself in 2 ​hours, and Bettina can clear the snow by herself in 5 hours. After Bettina has been working for 1-hour, Ken is able to join her. How much longer will it take them working together to remove the rest of the​ snow?

Answer 1

It will take 5.6 hours

Explanation:

If Ken (K) can clear in two hours and bettina (B) in five hours then;

5K=2B; If B=1 K=2/5 = 0.4 (2-0.4=1.6) plus 4 from B are 5.6 or also: If B=4 (Bettina started 1 hour later 5-1=4) K=8/5=1.6 then K+B=1.6+4=5.6 h