Question 23627
{{{(5n^2-2ny+3y^2)-(9n^2-8ny-10y^2)}}}


Remove the parentheses, multiplying the last quantity by -1:
{{{5n^2 -2ny +3y^2 - 9n^2 + 8ny + 10y^2}}}


Combine like terms:
{{{-4n^2 +6ny + 13y^2}}}


R^2 at SCC