# Fundamental Property Applications

## Determination of the unknown term of a ratio

Examples:

• Determine the value of x in proportion:

Solution:

5 x = 8. 15 (applying the fundamental property)
5 x = 120
x = 24
Therefore, the value of x é 24.
• Determine the value of x in proportion:

Solution:

5 (x-3) = 4. (2x + 1) (applying the fundamental property)
5x - 15 = 8x + 4
5x - 8x = 4 + 15
-3x = 19
3x = -19x =
Therefore, the value of x é .
• The numbers 5, 8, 35 and x, in that order, form a proportion. Determine the value of x.

Solution:

(applying the fundamental property)
5 x = 8. 35
5x = 280

x = 56
Therefore, the value of x é 56.

## Problem solving involving proportions

Example:

• In a saline of each cubic meter (m3) of salt water, 40 dm3 of salt To get 2 m3 salt, how many cubic meters of salt water are needed?
Solution:
The amount of salt removed is proportional to the volume of salt water. We indicate by x the amount of salt water to be determined and set the proportion:

Remember that 40dm3 = 0.04m3.
(applying the fundamental property)
1 . 2 = 0.04. x
0.04x = 2

x = 50 m3
So it takes 50 m3 of salt water.
Next: Proportional Fourth