In 1969, 85% of freshmen considered the objective developing a philosophy of life essential. since then, the percentage has decreased by approximately 0.9 each year. by which year would 35% or college freshmen consider that important?

Alright, since it decreases by 0.9 each year, the amount it decreases in x years = 0.9*x. We need to find out how long it takes to decrease 85-35=50 percent, so 0.9*x=50. Dividing both sides by 0.9, we get x=around 56 (we rounded up from 55+ something). Since we start at 1969, we get our end time to be 
1969+56 (since we rounded up) to get 2025. We add the 2 up because it takes 56 years to change

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