1) 4 3/7 : 1/7 = 31/7 : 1/7 = 31
2) 1 5/8 • 12 = 13/8 • 12 = 39/2 = 19,5
3) ( 1 1/3 )^2 : ( 1 1/2 )^2 = ( 4/3 )^2 : ( 3/2 )^2 = 16/9 : 9/4 = 64/81
4) 31 - 19,5 + ( 64/81 ) = 11,5 + ( 64/81 ) = 11 1/2 + 64/81 = 11 81/162 + 128/162 = 11 209/162 = 12 47/162