SOLUTION: John can mow the lawn in three hours. Henry can mow the lawn in seven hours. If they work together how long will it take to mow the lawn? And could you please show the work so

Question 783768: John can mow the lawn in three hours. Henry can mow the lawn in seven hours. If they work together how long will it take to mow the lawn?
And could you please show the work so it will help me understand.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
John can mow the lawn in three hours. Henry can mow the lawn in seven hours. If they work together how long will it take to mow the lawn?
And could you please show the work so it will help me understand.
***
John can mow the lawn by himself in three hours, so, in one hour he can finish 1/3 of the job, his work rate.
Similarly, Henry can mow the lawn by himself in seven hours, so, in one hour he can finish 1/7 of the job, his work rate.
John and Henry working together can finish the job in x hours, so, in one hour they can finish 1/x of the job, their work rate.
..
sum of individual work rates=work rate working together

LCD=21x
7x+3x=21
10x=21
x=21/10=2.1
Working together how long will it take to mow the lawn? 2.1 hours

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