Math help.. again and again and again..?

Question

you can mow a lawn in 3 hours. your friend can mow the same lawn in 4 hours. if the two of you work together, how long will it take to mow the lawn?

Answer 1

Work (mowed lawns) = time x rate. Your rate is 1 lawn/3 hrs; your friend's rate is 1 lawn/4 hrs.

1 mowed lawn = (Time, hrs) x (1 lawn/3 hrs + 1 lawn/4 hrs)

Time, hrs = 1/(1/3 + 1/4) = 1.71 hrs.

Answer 2

It's a rate problem (kind of like rt=d). "You" mows at a rate of 1/3 lawns per hour; "friend" mows at a rate of 1/4 lawns per hour. Together mowing at a rate of
1/4 + 1/3 = 3/12 + 4/12 = 7/12 lawns per hour.

So it takes 12/7 hours to mow a lawn; that is, 720/7 minutes
( equals approx 1 hr 43 min.)

Answer 3

I am no nerd or anything but I believe the answer should be seven the 3 hours you can mow the lawn + the four hours your friend can mow the lawn= seven.

Answer 4

I do 1/3 of the job in 1 hr, x/3 in x hr. Similarly, friend does x/4 of the job, and together we do 1 whole job.

x/3 + x/4 = 1
7x = 12
x = 12/7 = 1 5/7 hr.