Question

a) x/7 = 6/21 b) -5/y = 20/28

Answer 1

a) x/7 = 6/21

<=> x . 21 = 7 . 6

<=> x . 21 = 42

<=> x = 42 : 21

<=> x = 2

Answer 2

b) -5/y = 20/28

<=> y . 20 = -5 . 28

<=> y . 20 = -140

<=> y = -140 : 20

<=> y = -7

Vậy y = -7

Answer 3

a) x/7 = 6/21

<=> x . 21 = 7 . 6

<=> x . 21 = 42

<=> x = 42 : 21

<=> x = 2