__Category__: Algebra"Published in Newark, California, USA"

Joaquin can plow his farm in 4 days. He and his eldest son can finish plowing the farm in 2 days. With his youngest son helping, the three can finish the work in 1 ½ days. Alone, how long it will take the youngest son to plow the farm?

__Solution__:

The word problem is about a work problem. If there are at least two or more people to work in a certain job, then they will finish their work in lesser time. If there are lesser people to work in a certain job, then they will finish their work in longer time. Because of these statements, the working equation for this type of problem is rational linear equation. Let's start to analyze the word problem as follows

Joaquin can finish his work alone = 4 days

Joaquin and his eldest son = 2 days

Joaquin, his eldest son, and youngest son = 1 ½ days

His eldest son can finish his work alone = x days

His youngest son can finish his work alone = y days

Next, write the working equation for Joaquin and his eldest son in order to get the number of days that his eldest son can plow the farm alone as follows

Multiply the both sides of the equation by their LCD, which is 4x as follows

His eldest son can plow the farm alone in 4 days also. Finally, write the working equation for Joaquin, his eldest son, and his youngest son in order to get the number of days that his youngest son can plow the farm alone as follows

Multiply the both sides of the equation by their LCD, which is 6y as follows

Therefore, his youngest son can plow the farm alone in

**6 days**.