You can only add exponents if you are multiplying two of the same variable together. For example,

You take them away if you are dividing.
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In a polynomial equation, you can add together two of the same variable if they have the same exponent
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Or you can take them away in a similar fashion,
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But you cannot add two (or more) different exponents,
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(it does not get any simpler)
I hope this has answered your question, if not, leave a comment and I'll update the answer.
Answer:
Can you please take a better picture
Step-by-step explanation:
The answer to the question is
If he wants to earn $1000, it means that $1000 must be 20% of his overall sales.
1000 = 20% * x
1000 = 20/100x
1000 = 0,2x / ÷ 0,2 (both sides)
x = 5000
Answer: A salesman must sell products for $5000 to earn $1000.