Question

A spaceship landed near Alex's house. Alex saw that the aliens who walked out had 3 legs each. He counted a total of 24 legs. If ${}^{\prime }{x}^{\prime }$ is the number of aliens, find the equation for the number of legs of the aliens.

• A. $3x=24$
• B. $24x=3$
• C. $x+3=24$

Answer 1

The correct option is A $3x=24$

We know that each alien has 3 legs.
The number of aliens = $x$
$\therefore$ Total number of legs = $3\times x=3x$

As per the given question, total number of legs = $24$
Hence, equating both the quantities we get,
$3x=24$
This is the required equation.

Let the total number of aliens are 9.
We check the validity of the assumption we substitute the value of $x$ in the above equation.
$3x=24$
$\Rightarrow 3\times 9=24$
$\Rightarrow 27=24$
$\Rightarrow \text{Left hand side}\ne \text{Right hand side}$

Hence, the assumption that the total number of aliens as 9 is not correct.