Question

3/9=b/12
b/5=6/15
2/9=8/b
10/b=30/33

Answer 1

3/9=b/12

9b = 12*3

9b = 36

b = 36 : 9

b = 4

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b/5=6/15

15b = 6*5

15b = 30

b = 30 : 15

b = 2

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2/9=8/b

2b = 9*8

2b = 72

b = 72 : 2

b  36

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10/b=30/33

30b = 33*10

30b = 330

b = 330 : 30

b = 11