Week 16 – Applications of Rational Expressions

Rational expressions can be used to solve real-world problems. To solve the problem understand what is being asked, then use a variable for the missing number, write an equation using the given information, and then solve it.

Here is a problem involving proportions:

How much bleach should be added to 47 L of water to make a solution that is 6% bleach?

The total volume will be 47 + x, x is the amount of bleach that is needed.

6% can be expressed as .

An equation for this problem is  = .

To solve this, we can cross multiply. So, (100)(x) = 6(47+x)

100x = 282 + 6x

Subtract 6x from both sides: 94x = 282

Solve for x by dividing each side by 94.

x = 3, so 3 L is needed to make a solution that is 6% bleach.