1) Each of the ratios can be reduced to 1 : 5, Since both can be reduced to the same ratio, the do form a proportion.
4 : 20 = 1 : 5
6 : 30 = 1 : 5
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2) The first ratio can be reduced to 1/2. The second ratio is not 1/2 and cannot be reduced. Since they are different ratios, they do not form a proportion.
