You have reading homework every 6 days and science homework every 15 days. if you have homework in both today when will you have homework in both subjects again on the same day?

Do you remember when you were learning about the "Least Common
Multiple" of two numbers, and you were wondering why you had to learn
it, because you were so sure that you'd never need to use it ?  Do you
remember that ?

Well, HERE's where you get to use it.  This question is just looking for
the LCM of 6 and 15 .  THAT's how many days it will be before you get
homework in both subjects on the same day again.

(It's not 90 days, and it's not 60 days.)

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