45×43/44
=（44+1）×43/44
=44×43/44+1×43/44
=43+43/44
=43又43/44
43×43/44
=（44-1）×43/44
=44×43/44-1×43/44
=43-43/44
=42+1-43/44
=42+1/44
=42又1/44