math
posted by nikki .
8a^2+5ab12a^26(2a^24ab10n^2)

Is the n^2 supposed to be an a^2 ?
If so, you can combine three pairs of terms. Otherwise, two pairs.
Just multiply each term in parentheses by 6 and combine "like" terms.
You may also able to factor, after that.
You should try this yourself instead of looking for a web site (including jiskha) to do it for you.