=5/21X21/5X22/5
=1X22/5=22/5
=11/15-(2/15+1/2)
=11/15-2/15-1/2
=9/15-1/2
=3/5-1/2
=6/10-5/10=1/10
13/98X99
=13/98X(98+1)
=13+13/98
=13又98分之13
希望能帮你忙,懂了请采纳,
=5/21X21/5X22/5
=1X22/5=22/5
=11/15-(2/15+1/2)
=11/15-2/15-1/2
=9/15-1/2
=3/5-1/2
=6/10-5/10=1/10
13/98X99
=13/98X(98+1)
=13+13/98
=13又98分之13
希望能帮你忙,懂了请采纳,