ONE EIGHTH OF TONYS BOOKS ARE MYSTERY BOOKS. HE HAS 3 BOOKS. HOW MANY BOOKS DOES TONY HAVE IN ALL

 If he has 3 mystery books, and those are 1/8 of his whole collection, he has 24 books.

Step-by-step explanation:

3 = 1/8 × x

multiply both sides by the reciprocal of 1/8 which is 8/1 ("flipped fraction")

8 × 3 = 8/1(1/8) x  When you multiply a fraction by its reciprocal, it produces 1, so it "cancels" in the multiplication

24 = x

This may seem complicated, but understanding the process will help you solve more complicated questions like this in the future, I hope.

according to the triangle sum theorem, all the angles in a triangle must add up to 180 degrees. if we know one angle is already 90, we do 180-90=90. the other 2 angles must add up to 90, exactly.

step-by-step explanation: