Question

1)7:15=x:45
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Answer 1

Вот правильный ответ уверенно на все 100%

Answer 2

Используем здесь формулу пропорций:

$\frac{a}{b} = \frac{c}{d} \\ ad = bc$

1) 7:15 = x : 45

15x = 45*7 = 315

x = 315:15 = 21

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2) 8/14 = x/21

14x = 21*8 = 168

x = 168:14 = 12

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3) y : 3 1/5 = 4 1/2 : 2 1/4

2 1/4y = 3 1/5 * 4 1/2 = 16/5 * 9/2 = 72/5

y = 72/5 : 2 1/4 = 72/5 * 4/9 = 32/5 = 6 2/5

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4) 3 2/5 : x = 6 4/5 : 1 1/3

17/5 : x = 34/5 : 4/3

34/5x = 17/5 * 4/3 = 68/8 = 8 4/8

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5) 7/x = 42/5

42x = 7*5 = 35

x = 35/42 = 5/6

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6) 4 3/4 : 7 1/8 = x : 12

19/4 : 57/8 = x : 12

57/8x = 12*19/4 = 57

x = 57 : 57/8 = 57 * 8/57 = 8