Question

Calculati:

a) 7/15 -{ 5/12 + { 2/3 - (3/4 -3/5)]}
b) 3/10 +{ 5/16 - [ 7/20 - ( - 2/5 - 9/40 )]}
c) 1/6 - {7/48 + [ 5/32 -( 5/12 - 2/3 )]}
d) 3/8 - {9/28 + [ 5/24 - ( -4/21 +3/14)]}


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Answer 1

a) 7/15 -{ 5/12 + { 2/3 - (3/4 -3/5)]} =7/15 -{ 5/12 + { 2/3 - (15/20 -9/20)]}=
=7/15 -[ 5/12 + ( 2/3 - 6/20)]=7/15 -[ 5/12 + ( 2/3 - 3/10)]=7/15 -[ 5/12 + ( 20/30 - 9/30)]=7/15 -[(5/12 + 11/30)=28/60- (25/60+22/60)=28/60-37/60=
= -9/60= -3/20

b) 3/10 +{ 5/16 - [ 7/20 - ( - 2/5 - 9/40 )]}= 3/10 +{ 5/16 - [ 7/20 - ( - 16/40 - 9/40 )]}= 3/10 +{ 5/16 - [ 7/20 - ( - 25/40 )]}=3/10 +[5/16 -( 7/20 -25/40 )]=
=3/10 +[5/16 -( 14/40 -25/40 )]=3/10+(5/16+11/40)=3/10 +25/80+22/80)=
=24/80+47/80=71/80

c) 1/6 - {7/48 + [ 5/32 -( 5/12 - 2/3 )]}=1/6 - {7/48 + [ 5/32 -( 5/12 - 8/12 )]}=
=1/6 - [7/48 + (5/32 +3/12 )]=1/6-[7/48+(15/96+24/96)]=1/6-(7/48+39/96)=
=1/6-(14/96+39/96)=1/6-53/96=16/96-53/96= -37/96

d) 3/8 - {9/28 + [ 5/24 - ( -4/21 +3/14)]}=3/8 - {9/28 + [ 5/24 - ( -8/42+
9/42)]}=3/8 - [ 9/28 + ( 5/24 - 1/42)]= 3/8 - [ 9/28 + (35/168 - 4/168)]=
 =3/8 - (54/168 +31/168)=3/8-  85/168 =  63/168-85/168= -22/168=-11/84