Math Problem Solving
posted by Johnny .
Jay and Mark run a lawn mowing service. Mark's mower is twice as big as Jay's, so whenever they both mow, Mark mows twice as much as Jay in a given time period. When Jay and Mark are working together, it takes them 4 hours to cut the lawn of an estate. How long would it take Mark to mow the lawn by himself? How long would it take Jay to mow the lawn by himself?

Let Jay's lawn mowing rate be J lawns per hour. Marks rate is 2J per lawns per hour.
To do one lawn
4 hours = 1/(J + 2J) = 1/(3J)
J = 1/12 lawn per hour
(Jay would need 12 hours to do the lawn)
Mark's rate is 1/6 lawn/hour, so one lawn would take him 6 hours. 
It takes John 4 hours to mow a lawn. It takes Maria 3 hours to mow the same lawn. How long would it take if they worked together?

i don't know i want help to solve the problem solving