3. 5/6 × ( 3/10 + 1 (1/2) ) , 8/9 : ( 3/4 + 1/2 ) ,( 1/3 + 2/9 ) : ( 9/10 - 2/5 ) , 1(1/5) × ( 3/4 - 1/3 ) , ( 2/3 + 2/7 ) : 1(1/14) , ( 4 - 2/3 ) × ( 1(1/2) - 3/4 ) 4. (1,2 + 0.9) : ( 0.9 - 0.55 ) , (3.6 - 0.9) ÷ ( 1.8 - 1.65 ) , ( 1.8 + 0.5 ) × ( 2 - 0.7 ) , ( 3.75 + 2.5 ) × ( 1 - 0.96 )