Question

How do you solve `\frac { 5} { 1} = \frac { x } { 4}`?

Answer 1

The variable `x` equals 20.

Explanation:

There are two ways to solve this:

First method: You can find a common multiplier or divider between the denominators, then apply that to the numerators. In this example, the denominator in the known fraction is 1, and can be multiplied by 4 to yield the denominator of the unknown fraction, which is 4. We can also use the multiplier of 4 in the numerator of the known fraction to calculate the numerator of the unknown fraction. Multiplying 5 by 4 gives you 20, which is the answer.

Second method: You can "cross multiply" by multiplying the numerator of either fraction to the denominator of the other fraction, then setting the products equal to each other. For example, 5 multiplied by 4 gives you 20. `x` multiplied by 1 gives 1`x`. This gives us the equation 20 = 1`x`. We can divide by 1 on both sides to make the variable stand alone, though that doesn't make much of a difference in this particular problem. The end result will also be 20 in this method.