1/3n+9(-2)=-2/3n+7

Alright, we have to start with multiplying 9 x (-2). When you have a number in front of parentheses, you have to multiply those numbers. We do this first because parentheses comes before our other operations in the order of operations. To remember the order of operations, remember PEMDAS!

Let's mutliply this out.

1/3n+9(-2)=-2/3n+7

1/3n+(-18)=-2/3n+7        ---Add 2/3n to both sides. This "clears" -2/3n from the right side

+2/3n          +2/3n          ---1/3n plus 2/3n is really just n, because it comes out to 3/3n, and 3/3 is equivalent to 1

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n +(-18) = 7                    ---Now we add 18 to both sides. This "clears" -18 from the left side

     +18     +18

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n = 25

And that's it! As always, let me know if you need any more help.