What is x when 18 divided by x equals 4?

To find the answer, just divide the dividend by the quotient: 18 ÷ 4 = 4.5

To prove this, let's compute 18 divided by 4.5: $\frac{18}{4.5} = 4$

How does it work?

Asking what the value of x could be when 18 divided by x gives a result of 4, is equivalent to solving the following equation:

$\frac{18}{x} = 4$

Multiply both sides by x: $\frac{18 x}{x} = 4 x$
$\frac{18 x}{x}$ is equivalent to $\frac{x}{x} \times 18$ , which simplifies to $1 \times 18$ (or just $18$ ).
Thus, the equation becomes: $18 = 4 x$
To find x, divide both sides by 4: $\frac{18}{4} = \frac{4 x}{4}$
Which gives, after simplification: $4.5 = x$ (or $x = 4.5$ )

So, if the dividend is 18 and the quotient is 4, the divisor is 4.5.