4分之3除以2分之3与2.8的和,商 = 3/4 ÷ ( 3/2 + 2 + 4/5 ) = 3/4 ÷ ( 3 + 1/2 + 4/5 ) = 3/4 ÷ [ 3 + (5 + 8 )/10 ] = 3/4 ÷ ( 30+ 13 ) /10= 3/4 x 10 /43= 3/2 x 5/43= 86分之 15