Video: Multiplying Fractions with Unlike Denominators

Evaluate (−7/5) × (3/4).


Video Transcript

Evaluate negative seven-fifths multiplied by three-quarters.

In order to multiply any two fractions, we multiply the two numerators and then, separately, the two denominators. The fraction 𝑎 over 𝑏 multiplied by the fraction 𝑐 over 𝑑 is equal to 𝑎𝑐 over 𝑏𝑑. The two numerators in our question are negative seven and three. We need to multiply negative seven by three. Multiplying a negative number and a positive number gives a negative answer. Therefore, negative seven multiplied by three is equal to negative 21.

The two denominators are five and four. Five multiplied by four is equal to 20. This means that negative seven-fifths multiplied by three-quarters is equal to negative 21 over 20. 21 divided by 20 is equal to one remainder one. Therefore, negative 21 over 20 is the same as negative one and one twentieth. Either one of these answers are correct for the calculation negative seven-fifths multiplied by three-quarters.

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