Question

Efetue as adiçoes e subtraçoes a seguir.
a)4/7 + 2/7 =
b)8/5 - 3/5 =
c)3/10 + 1/4
d)4/5 - 2/3 =
e)5/8 - 1/4 =
f)1 1/4 + 1/6
g)1 3/10 - 8/9=
h)3/25 + 2/5 =
i)3/4 + (4/5 - 3/10)=
j)5/8 - 3/8 - 1/8
com as contas por favor!

Answer 1

a)4/7 + 2/7 =   (4+2)/7 = 7/7 = 1

b)8/5 - 3/5 =  (8-3)/5   = 5/5   =  1

c)3/10 + 1/4  = (12+11)/40 = 33/40

d)4/5 - 2/3 =  (12-10)/15 =2/15

e)5/8 - 1/4 =  (5-2)/8 =3/8

f)  1 1/4 + 1/6  = (33+2)/12 = 31/12

g)  1 3/10 - 8/9= ( 117-80)/90 = 37/90

h)  3/25 + 2/5 =  (3+10)/25 = 13/25

i) 3/4 + (4/5 - 3/10) =  3/4 + [(8-3)/10] = 3/4 + [5/10] = 3/4+1/5 = (15+4)/20 = 19/20

j) 5/8 - 3/8 - 1/8 = (5-3-1)/8 = 1/8

Answer 2

a) 4/7 + 2/7 = 6/7

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b) 8/5 - 3/5 = 5/5 = 1

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c) 3/10 + 1/4 =  

mmc (4, 10) = 20

6 + 5/20 = 11/20

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d) 4/5 - 2/3 =  

mmc (5,3) = 15

12 - 10/15 = 2/15  

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e) 5/8  - 1/4 =  

mmc (8,4) = 8

5 - 2/8 = 3/8  

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f) 1 1/4 + 2 1/6 =

mmc de (4,6) = 12  

5/4 + 13/6 = 15 + 26/ 12 = 41/12  

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g) 1 3/10 - 8/9 =

mmc de (9,10) = 90

9 x 13/90 - 10 x 8/90 = 117/90 - 80/90 = 37/90

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h) 3/25 + 2/5 =  

mmc de (25,5) = 25

3 + 10/25 = 13/25

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i) 3/4 + (4/5 - 3/10) =

primeiro descobrir o que está em parênteses!

4/5 - 3/10 = 8 - 3/10 = 5/10

3/4 + 5/10 = 15 + 10/20 = 25/20 (dividindo por 5) = 5/4

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j) 5/8 - 3/8 - 1/8 =

os denominadores são iguais (8),  efetuar as operações com os numeradores.

(5-3-1)/8 = 1/8