1又1/4)÷(1又1/2)-(3/4+7/8)÷(13/16)=5/4*2/3-13/8*16/13
=8/15-2
=8/15-30/15
=-22/15
(1又1/4)÷(1又1/2)-(3/4+7/8)÷(13/16)
=5/4÷3/2-13/8÷13/16
=5/4x2/3-13/8x16/13
=5/6-2
=5/6-12/6
=-7/6
=1.25/1.5-1.875/0.8125
=5/6-30/13
=-135/78
=-45/26
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