a) 1/2 ÷ x = 1/2 - 3/4

1/2 ÷ x = 2/4 - 3/4

1/2 ÷ x = -1/4

x = 1/2 ÷ (-1/4)

x = 1/2 × (-4/1)

x = -4/2 = - 2/1 = -2

Vậy x = -2

b) x - 1 = 3/5 × 15

x - 1 = 9

x = 9 + 1

x = 10

Vậy x = 10

c) x + 2,5 = 1,4

x = 1,4 - 2,5

x = - 1,1

Vậy x = -1,1

a)A = (2,34 + 7,66) + (5,35 + 4,65)

A = 10 + 10

A = 20

Vậy A = 20

b)B = 2,13 × 75 + 2,13 × 25

B = 2,13 × (75 + 25)

B = 2,13 × 100

B = 213

Vậy B = 213

c)C = 1/3 - 1/3 × 4/3

C = 1/3 - 4/9

C = 3/9 - 4/9

C = -1/9

Vậy C = -1/9

a) -3/8=-9/24

5/-12=-10/24

Vì -9> -10 nên -9/24> -10/24 Do đó -3/8>5/-12

b) 3131/5252=31/52

Vì 31=31 nên 31/52=31/52 Do đó 3131/5252=31/52