What is x when 84 divided by x equals 20?

To find the answer, just divide the dividend by the quotient: 84 ÷ 20 = 4.2

To prove this, let's compute 84 divided by 4.2: $\frac{84}{4.2} = 20$

How does it work?

Asking what the value of x could be when 84 divided by x gives a result of 20, is equivalent to solving the following equation:

$\frac{84}{x} = 20$

Multiply both sides by x: $\frac{84 x}{x} = 20 x$
$\frac{84 x}{x}$ is equivalent to $\frac{x}{x} \times 84$ , which simplifies to $1 \times 84$ (or just $84$ ).
Thus, the equation becomes: $84 = 20 x$
To find x, divide both sides by 20: $\frac{84}{20} = \frac{20 x}{20}$
Which gives, after simplification: $4.2 = x$ (or $x = 4.2$ )

So, if the dividend is 84 and the quotient is 20, the divisor is 4.2.