a)5/9 -(1/3)^2 = 5/9 -1/9 = 4/9

b)1/5 x (-3)/2 + (-17)/2 . 1/5=1/5 .(-3)/2 + (-17)/2=1/5 .[ (-3/2) +(-17)/2] = 1/5 .( -12)/2=1/5 .( -6)= -6/5

c)1 + (-2/5 + 11/13) - (3/5 - 2/13)=1 + (-2)/5 + 11/13 - 3/5 + 2/13=1 + (-2/5 - 3/5) - +(11/13 + 2/13)=1 +( -1 )- 1 =1 + 2= 3

a)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 + 5/9 + 1/4 + 1/12 + 3/5 + 1/35 - 7/45

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

=(6/9 + 5/9 )+ (3/12 + 1/12) + (21/35 + 1/35 )- 7/45

=11/9 + 1/3 + 22/35 - 7/45 =(1/9 + 3/9) + 22/35 - 7/45=14/9 + 22/35 - 7/45=490/3 15 + 198/315 + 7/45=688/315- 7/45= 66/315 + 49/315 = 71/35

b)Q=(5- 3/4 + 1/5) +( 6 + 7/4 + 8/5) -( 2 - 5/4 + 16/15)

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

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

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

=3 + (-5)/4 +( -7)/5=60/20 - 25/20+28/20=-113/20

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

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

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

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

=1 - 1 + 1= 0 + 1= 1

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

=0,25 + 3/5 - 1/8 + 2/5 - 5/4

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

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

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

=1 - 1 - 1/8

=0- 1/8 =-1/8