There are 950 books in a two-story bookshelf. If you take 45 books from the upper level and put 55 books on the lower level, then the books from the upper level.
Let the upper and lower books be 2x and 3x respectively, then there is (2x-48): (2x+45): 5x = 0.7.
2X+45 = 3.5 times
1.5X=45
X=30
Up 60 degrees, down 90 degrees.
*** 150