(-11又1/5)/0.5-(-21又1/4)/0.5+(-10又1/3)/0.5
=(-11-1/5)/0.5-(-21-1/4)/0.5+(-10-1/3)/0.5
=[(-11-1/5)-(-21-1/4)+(-10-1/3)]/0.5
=(-11-1/5+21+1/4-10-1/3)/0.5
=(-11+21-10-1/5+1/4-1/3)/0.5
...
(-11又1/5)/0.5-(-21又1/4)/0.5+(-10又1/3)/0.5
=(-11-1/5)/0.5-(-21-1/4)/0.5+(-10-1/3)/0.5
=[(-11-1/5)-(-21-1/4)+(-10-1/3)]/0.5
=(-11-1/5+21+1/4-10-1/3)/0.5
=(-11+21-10-1/5+1/4-1/3)/0.5
...