My math teacher sucks, please help.

Concept: Rate of Change

We are told that the rate of change is 3x d/dx and we want to find the rate for 12 hours hence we do 12÷ 3 to get 4 hours You are told she babysat for 2 hours, each day for a total of 10 days = 20 hours. She earned 180 dollars so 180/20 hours = $9 per hour So you have a table and it tells you that for every quart you need 4 bags of tea. Hence for 24 bags we will get a result of 6 quarts of teaYou are told you have 35 total items between x= bottle and y= bars. You have 7 friends and each carry 3 water bottles = 21 water bottles. Hence 35-21= 14 bars Rate positively and give brainlist

Okay so for every triangle has three angles that always add up to 180 degrees. and to tell the difference between whether they are secure, right or obtuse is that acute: has one angle that is less than 90 degrees. right triangle means there is at least one angle that is exactly 90 degrees. and an obtuse angle has an angle that is bigger than 180 degrees. i’ll do #13 as an example: 13. 40 and 50 so if every triangle has 180 degrees 40+50= 90 degrees then180-90= 90 degrees so the third angle is 90 degrees and because this triangle has a 90 degree angle it means it is a right triangle