Try this (I'll put asterisks every time I give a little more of a hint):

You're probably trying to write equations for how fast they mow--at least, that was my first thought, but try writing equations for how much lawn they have left to mow.

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Assuming it's the same size lawn, let's give the lawn a value of 1, since it's 1 whole lawn (if the question were given in percents, we'd make it 100).

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How much lawn do they each have left after 1 minute? After 2 minutes? After m minutes?

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You're going to have three equations and three variables. Make your first equation to find how much lawn K has left after m minutes, and your second to find out how much lawn Z has after m minutes. Can you figure out your third equation?

(equations follow, so if you want to work it out for yourself based on the above, stop now

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After 1 minute, K has mowed 1/24 of the lawn, so he has 23/24 left. After 2 minutes, he has 22/24 left. So after m minutes, he has 1-m/24 left. Follow similar reasoning with Z to get the first two equations:

k=1-m/24

z=1-m/36

That's two equations and three variables, but we actually want to solve it. Specifically, we want to know when z=2k. So that's our third equation.

A little substitution and solve for m...

Max M.

03/18/20

Kaito D.

Thank you so much! It helped me a lot! I got solution and it was 18 minutes!01/31/20