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Explanation:</h2><h2>
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Because we perform something like common factor, so this guarantee that corresponding digits have regarding coefficients have the same place value. Remember that a number written in scientific notation is given by the product of a number between 1 and 10 and another number that is power of 10. For example, let's write two examples about this:
Addition:

Addition:

Subtraction:

Answer:
75%
Step-by-step explanation:
Percent yield = experimental yield / theoretical yield * 100
= 900 / 1200 * 100 (remember that 1,000 g = 1 kg)
= 75
I'm really sorry, I'm not the best at this, but I did all the equations the best to my knowledge and came up with these 3 answers
(2,-1) which equaled -7
(5,4) which equaled -11
and (0,-9) which equaled - 9
Again I'm really sorry if this didn't work. :( God bless and good luck with future lessons.