The ratio (or raicios) are 2:4, 4:8, 8,16, so on and so on.
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The question states, vanilla cake calls for 2 cups of sugar for every 4 eggs. So basically you would add 2 every time you count to 4. Ex: 4 x 3 = 2 x 3,
4 x 6 = 2 x 6. Whatever happens to one side, has to happen to the other.