21/16: (3 7/15x+4 5/6): 3 5/9=1 1/3

2 1/16:(3 7/15x+4 5/6):3 5/9 =1 1/3 
(33/16):(52x/15+29/6):(32/9)=4/3 
(33/16):((104x+145)/30):(32/9)=4/3 
33*30*9/16*(104x+145)*32=4/3 
x=-51225/39936