2. Let the base angle be x and the top angle be 2x.
2x+x+x= 180
x=45
That is, the base angle is: 45 and the top angle is: 90.
3. There are as many completed tasks as the rest, that is, 1/2.
* * * Yes:15/(1/2-1/3) = 90.
4. Solution: In the past, bookcase B had 5X books and bookcase A had 2X books.
(2X+360):(5X)=5:8
Internal product = external product
16X+2880=25X
9X=2880
X=320
B There are 5X books on the shelf.
320*5= 1600 (Ben)