Answer:
7.5 hours
Step-by-step explanation:
The key here is to find out how much can be done in the same amount ot time
the least common multiple of 5 hrs and 3 hrs is 15hrs
In 15 hours:
- At 5 hours per lawn Norton could mow 15/5 = 3 lawns
- At 3 hours per lawn together thay could mow 15/3 = 5 lawns
In 15 hours Jesse would mow 5 - 3 = 2 lawns
15 hours/ 2 lawns = 7.5 hours per lawn
7.5 hours
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Here's the math
1 lawn/5hrs + x = 1 lawn / 3hrs
1/5 + x = 1/3
Subtract 1/5 from both sides
x = 1/3 - 1/5
x = 5/15 - 3/15
x = 2/15
x = 2lawns/15 hrs
15hrs/2lawns = 7.5 hrs per lawn
7.5 hours
