What is x when 90 divided by x equals 4?

To find the answer, just divide the dividend by the quotient: 90 ÷ 4 = 22.5

To prove this, let's compute 90 divided by 22.5: $\frac{90}{22.5} = 4$

How does it work?

Asking what the value of x could be when 90 divided by x gives a result of 4, is equivalent to solving the following equation:

$\frac{90}{x} = 4$

Multiply both sides by x: $\frac{90 x}{x} = 4 x$
$\frac{90 x}{x}$ is equivalent to $\frac{x}{x} \times 90$ , which simplifies to $1 \times 90$ (or just $90$ ).
Thus, the equation becomes: $90 = 4 x$
To find x, divide both sides by 4: $\frac{90}{4} = \frac{4 x}{4}$
Which gives, after simplification: $22.5 = x$ (or $x = 22.5$ )

So, if the dividend is 90 and the quotient is 4, the divisor is 22.5.