You know the distributive property, right? That means whenever you have something like:

x(y+z)

You can multiply the number outside the parentheses by each term in the parentheses, resulting in:

xy + xz

We will use that here, so:

n-(5n+2)=3(n-1)

Is the same thing as:

n-1(5n+2)=3(n-1)

...right? So you just take -1 times each term in the first parentheses and 3 times each term in the second parentheses, resulting in:

n-5n-2=3n-3

Then you just combine like terms and get the n variable to one side, then divide out the multiplier:

-4n-2=3n-3

-4n-2-3n+2=3n-3-3n+2

-7n=-1

n=1/7

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