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A=2/7+11/71/4=(2x4)/(7x4)+(11x4)/(7x4)+(7x1)/(7x4)=8/28+44/28+7/28=59/28

B=1/12+1/16=(1x4)/(12x4)+(1x3)/(16x3)=4/48+3/48=7/48

C=5/12-3/4=5/12-(3x3)/(4x3)=5/12-9/12=-4/12(-1x4)/(3x4)=-1/3

D=4+2/3=12/3+2/3=14/3

E=4x2/3=8/3

F=-3/5x1/2=-3/10

G=-7/3x(-6)x2/-14=42/3x2/-14=84/-42=-2

H=3(1/4-1/5)=3((1x5)/(4x5)-(1x4)/(5x4))=3(5/20-4/20)=3(1/20)=3/20

I=(1/4-2/3)(1/3-1/5)=((1x3)/(4x3)-(4x2)/(4x3))((5x1)/(5x3)-(1x3)/(3x5))=(3/12-8/12)(5/15-3/15)=-5/12x2/15=-10/180=(-1x10)/(18x10)=-1/18

J=5/11-8/11x5/4=5/11-40/44=(5x4)/(11x4)-40/44=20/44-40/44=-20/44=(-5x4)/(11x4)=-5/11

K=5/6÷20/21=5/6x21/20=105/120=(15x7)/(8x15)=7/8

L=5/6÷20=5/6x1/20=5/120=(5x1)/(24x5)=1/24

M=3+1/5÷3-1/5=15/5+1/5÷15/5-1/5=16/15÷14/15=16/15x15/14=240/210=24/21=(3x8)/(7x3)=8/7