SOLUTION: Please help me Jack usually mows his lawn in 3 hours. Marilyn can mow the same yard in 7 hours. How much time would it take for them to mow the lawn together??

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Please help me Jack usually mows his lawn in 3 hours. Marilyn can mow the same yard in 7 hours. How much time would it take for them to mow the lawn together??      Log On


   

Question 358631: Please help me
Jack usually mows his lawn in 3 hours. Marilyn can mow the same yard in 7 hours. How much time would it take for them to mow the lawn together??
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi,

Jack usually mows his lawn in 3 hours. Marilyn can mow the same yard in 7 hours.

Let x represent the time it takes them together

1/3 + 1/7 = 1/x

Mulitply thru with 21x to clear the denominators

7x + 3x = 21

10x = 21

x = 2.1 hrs together