The multiplication property of equality.

Answer:
Step-by-step explanation:

Week 24,assuming that both machines are cleaned at week 0, because multiples of 12 are 12, 24,36. And multiples of 8 are 8, 16, 24. 24 is also the LCM.
You have a lot of questions here, try breaking them up into multiple posts and you may get more responses.
I will help with some.
<span>(x+3)=0
The solution is just -3.
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3m(m-4)=0
The two solutions are 0 and 4.
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(r-3)(r+2)=0
The two solutions are and 3 and -2.
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I hope this gets you started in the right direction.
The answer is x= 9 and -3
You must fine 2 number that multiply to equal -27 and add to equal -6
(x-9) (x+3)
Then equal the parts of the binomial to zero
x - 9 = 0
x + 3 = 0
You must get x by its self.
When you do so, you'll have the answer as -3 and 9