A=(2/7.1/4-1/3.2/7):(2/7.3/9-2/7.2/5)

=2/7.(1/4-1/3):(2/7.(3/9-2/8))

=2/12-4/12):(15/45-18/45)

=-1/12.45/-3=5/4

B=(1/5-2/7).3/4-3/4.(1/3-2/7)

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1/5.2/7-2/7-1/3+2/7+3/9)=3/4.1/5

=3/4.(1/5-2/7-1/3+2/7)

_________________

1/5-(2/7+3/9)-1/3918/63=21/63)

=3/4.(1/5-1/3)

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1/5-(18/63+21/63)-1/3(19/63+21/63)

=3/4.(1/5-1/3)

_____________________________

(1/5-1/3)18/63+21/63)

=3/4:39/63=3/4.21/13=63/52

3/5.6/7+3/7:5/3-2/7:1.2/3

=3/5.6/7+3/7.3/5-2/7:5/3

=3/5.6/7+3/7-3/5-2/7.3/5

3/5(6/7+3/7-2/7)

=3/5.1=3/5

B=(-13.2/5+-2/9:2.1/2+2/5.11/9).2.1/2

=(-13.2/5+-2/9:5/2+2/5.11/9).5/2

(2/5(-13-2/9+11/9)).5/2

2/5.(-12).5/2

=-12

C=(-4/5+5/7):2/3+(-1/5+2/7);2/3

=(-4/5+5/7-1/5+2/7):2/3

=((-4/5-1/5)+(5/7+2/7));2/3

=(-1+1):2/3

=0:2/3

=0

D=4/9:(1/15-2/3)+4/9:(1/11-5/22)

=4/9:(1/15-10/15)+4/9:(2/22-5/22)

=4/9.(15/-9)+4/9:(-3/22)

=4/9.(15/-9)+4/9.(22/-3)

=-20/27+(88/27)=-4

P=2/3-(-1/4)+3/5-7/45-(-5/9)+1/12+1/35

=2/3+1/4+3/5-7/45-(-5/9)+1/12+1/35

=2/3+1/4+3/5-7/45+5/9+1/12+1/35

=71/35

Q=(5-3/4+1/5)-(6+7/4-8/5)-(2-5/4+16/5)

=89/20-(6+7/4-8/5)-(2-5/4+16/5)

=89/20-123/20-(2-5/4+16/5)

=89/20-123/20-79/20

=113/20

A=(1/3-8/15-1/7)+(2/3+7/15+1.1/7)

=(1/3+2/3)-(8/15+7/15)=1/7+8/7

=1-1+1=1

B=0,25+3/5-(1/8-2/5-1.1/4)

=1/4+3/5-1/8+2/5-5/4

=(1/4-5/4)+(3/5+2/5)-1/8

=-1+1-1/8=1/8