Floor function

floor (r)  +  r  =  12.2  - r

floor (r)  +  2r   =   12.2

Note if  r = 4.1    we  have

floor (4.1)  + 2(4.1)  =  

4  +  8.2  =  

12.2

floor(r) + 2r = 12.2

12 < 3r < 13

4 < r < 4.6...

0.2÷2 = 0.1

0.1 for each of the r

given interval (4, 4 2/3) we have r = 4.1