I dont think the answer is 129 unless you typed the problem in wrong. Order of operations say to do everything inside the perenthesis first so you would do the 3*2 which is 6 then divide the 12 by 6 and you get 2. so your new equation is 8^2+9(2)-7. Next distribute the 9 to the 2 that is inside the perenthesis. Square root the 8 also. Now it is 49+18-7. The answer would be 60 ...?