Answer:
Only 4 is the right answer. The rest all are false.
C=300+1200x-100x. Find x if the total cost is 3,000
3,000 = 300 + 1200x -100x
3000 = 300 + 1100x
2700 = 1100x
2700÷1100=x
x=27/11
x = 2 5/11
Round to 3
First divide both sides by - 5,

Move the constant to the right side of the equation and change its sign (-4 => +4)

Add the numbers,

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I hope that helps you out!!
Any more questions, please feel free to ask me and I will gladly help you out!!
~Zoey