Multiply the cross products, and see if they are equal. If they are equal, the proportion is true. If they are unequal, the proportion is false.
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A ratio is simply a comparison between 2 numbers. Example- 4:3 A proportion is 2 fractions equal to each other or "proportionate".
The ratios a/b and c/d form a proportion is if their simplified forms are the same, or equivalently, if a*d = b*c
You tell by knowing the material and studying. If you have kept up with your work, it will be pretty obvious that the answer is true or false unless you have a sneaky teacher who makes really hard test questions.
a/b = c/d if and only if a*d = b*c.
direct proportion indirect proportion additive proportion partitive proportion