How to solve a proportion (7th grade math/prealgebra)

Proportion is defined as an equation of the type (ratio) = (ratio). I show three different ways of solving proportions:
1) a table of equivalent ratios
2) thinking of equivalent fractions
3) cross-multiplying.

In this second video, we have a typical situation where a proportion is useful: A car can travel 100 miles on 4.23 gallons of gas. How far can it travel on 7 gallons?

See also

Unit Rates — video lesson

Math Mammoth Grade 7 curriculum (pre-algebra)

Back to pre-algebra videos index

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