1/3×2+2/3÷1/2
=1/3×2+2/3×2
=2×(1/3+2/3)
=2
4×0.8×12.5×0.25
=4×0.25×0.8×12.5
=1×10
=10
29×17/28
=（28+1）×17/28
=28×17/28+17/28
=17+17/28
=17又17/28