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#magnitude #proportionality #ratios #algebra #inversemagnitudes #mathematics #ruleofthree Two magnitudes are directly proportional when, when multiplying one of them by any number, the other is multiplied by the same number. Likewise, two magnitudes are directly proportional if, when dividing one by any number, then the other is divided by the same number. A direct proportionality relationship is established between two magnitudes when: A greater quantity of the first magnitude corresponds to a greater quantity in the second magnitude, in the same proportion. A lesser quantity in the first magnitude corresponds to a lesser quantity in the second magnitude, in the same proportion. Another way to determine if two magnitudes are directly proportional is by their quotient. The quotient between two directly proportional magnitudes is always constant. Examples of direct proportionality problems Now, let's look at some examples of directly proportional quantities: 1 The weight of a product and its price are two directly proportional magnitudes. Let us note that if kg of tomatoes costs , then: kg of tomatoes will cost kg of tomatoes will cost ( cents) That is, more euros will be paid for more kilograms of tomatoes. Likewise, fewer euros will be paid for fewer kilograms of tomatoes. Let us also note that dividing the weight by the price always gives us a quotient.