Question 15517
The first step is to translate the problem from a word description to an algebraic equation: Let n be the missing number.

{{{3n + (n+7) = -11 - 2n}}} Simplify.
{{{4n + 7 = -11 - 2n}}} Add 2n to both sides.
{{{6n + 7 = -11}}} Subtract 7 from both sides.
{{{6n = -18}}} Divide both sides by 6.
{{{n = -3}}}