1) First, you have to add all the 3 pieces of wood
10+7.5+12= 29.5 ft.
Second, you have to add the pieces that he has used
5.2 +6.2= 11.4 ft
Third, you have subtract the used wood from the whole wood to get how many feet he didn't use
29.5 - 11.4=18.1 ft.
I hope it helped. But, sorry don't know how to do number 2.
To find the sum of the interior angles you use the formula (n-2)(180), where n is the number of sides. In this case, the number of sides is 12, so you get 1800 degrees. Then you divide by number of angles which is 12. So your answer is 150 degrees.
Hope this helps. Let me know if you have more questions.
