3/7-(1/2-3/7)+1/2 =3/7 - 1/2 + 3/7 + 1/2=3/7 + 3/7 =6/7.73÷0.8÷12.5=73÷(0.8×12.5)=73÷10=7.3.1/2×201-1/2=(1/2)×(201-1)=(1/2)×200=100.(1/3+1/8-1/24)÷1/24=(1/3+1/8-1/24)×24=(1/3)×24 +(1/8)×24 -(1/24)×24=8 +3 -1=10