*The length and breadth of a rectangle are in the ratio 5 : 4. Solution: Let the breadth of the rectangle be x cm Then, 5 : 4 :: 80 : x⇒ 5/4 = 80/x To get 80 in the numerator, we have to multiply 5 by 16. 4 by 16Thus, 5/4 = 80/(4 × 16) = 80/64So, x = 64Hence, breadth of the rectangle = 64 cm.*

A 30-inch tall model building was also used in the movie. First, write the proportion, using a letter to stand for the missing term.

We find the cross products by multiplying 20 times x, and 50 times 30. Study this step closely, because this is a technique we will use often in algebra.

In the given problem, we have to find the time taken by a person to type 390 words if the person takes 1 minute to type 30 words. This fraction must be proportional to the second fraction.

The second fraction has '390 words' in the numerator and the variable 'x' to represent the time which we have to find.

We are trying to get our unknown number, x, on the left side of the equation, all by itself.

Since x is multiplied by 20, we can use the "inverse" of multiplying, which is dividing, to get rid of the 20.

A proportion is simply a statement that two ratios are equal.

It can be written in two ways: as two equal fractions a/b = c/d; or using a colon, a:b = c:d.

This tutorial shows you how to use a proportion to solve! The idea of proportions is that a ratio can be written in many ways and still be equal to the same value.

That's why proportions are actually equations with equal ratios.

## Comments Using Proportions To Solve Word Problems