It takes leon 13 hours to seal his driveway working by hinself. If michael helps leon, they can seal the driveway in 7 hours. How long would it take michael to seal yhe drive way alone?

15.1667 hours (15 hours and 10 minutes)

Step-by-step explanation:

Using the concept of "distance = speed * time", we can formulate equations to solve this problem.

Let's call Leon's speed X, Michael's speed Y and the length of the driveway D.

If leon takes 13 hours alone, we can write the equation:

D = X * 13

If Michael helps Leon, we have this equation:

D = (X+Y) * 7

(The total speed is the sum of their speed, as they are working together)

Making the first equation equate the second, we have:

13*X = 7*X + 7*Y

7*Y = 6*X

X = (7/6)*Y

If we use this value of X in the first equation, we have:

D = 13*X = 13*(7/6)*Y = 15.1667*Y

So we have that Michael would take 15.1667 hours (15 hours and 10 minutes) to seal the driveway alone.