-7(n+9)-(7+2n)=-10n

First, expand;

-7(n+9)-(7+2n)=-10n

-7n-63-7-2n=-10n

Then, move all the terms in n on the same side;

-7n-2n+10n=+7+63

Can you take it from there?

Your answer should be 70

Just multiply the number outside the parantheses with the one inside:

-7n-63-7-2n = -10n

Group the same number together (n with n and without n with without n):

-9n -70 = -10 n

Then, solve for n:
-9n + 10 n (the sign change as you bring it to the other side) thus,

-9n + 10n = 70
n = 70

But... but... what's the pointof posting is the question is already more than a week old? And the question already answered? :confused: