Because you have to go in the order of PEMDAS, parenthesis, exponents, multiplication, division, addition, and subtraction. From what you are saying, 'why you must simplify 3 to the second power first' it seems that you have no parenthesis, so you move onto what is next, which is exponents, in this case, 3 to the power of two.
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Because he ended up paying $24 more than the actual price of the drill, this is the amount of interest he paid.
In total, the repairman pays $324 in 6 equal payments. So, each payment was

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Answer:
Step-by-step explanation:
A. (x, y) is not an equation.
B. 2 + 7 = 9 Not a linear equation, as there is no variable.
C. 3x + 5 = 20 This is a linear equation.
D. y = 2x + 1 This is a linear equation.