What is x when 28 divided by x equals 21?

To find the answer, just divide the dividend by the quotient: 28 ÷ 21 = 1.3333333333333

To prove this, let's compute 28 divided by 1.3333333333333: $\frac{28}{1.3333333333333} = 21$

How does it work?

Asking what the value of x could be when 28 divided by x gives a result of 21, is equivalent to solving the following equation:

$\frac{28}{x} = 21$

Multiply both sides by x: $\frac{28 x}{x} = 21 x$
$\frac{28 x}{x}$ is equivalent to $\frac{x}{x} \times 28$ , which simplifies to $1 \times 28$ (or just $28$ ).
Thus, the equation becomes: $28 = 21 x$
To find x, divide both sides by 21: $\frac{28}{21} = \frac{21 x}{21}$
Which gives, after simplification: $1.3333333333333 = x$ (or $x = 1.3333333333333$ )

So, if the dividend is 28 and the quotient is 21, the divisor is 1.3333333333333.