What is x when 42 divided by x equals 12?

To find the answer, just divide the dividend by the quotient: 42 ÷ 12 = 3.5

To prove this, let's compute 42 divided by 3.5: $\frac{42}{3.5} = 12$

How does it work?

Asking what the value of x could be when 42 divided by x gives a result of 12, is equivalent to solving the following equation:

$\frac{42}{x} = 12$

Multiply both sides by x: $\frac{42 x}{x} = 12 x$
$\frac{42 x}{x}$ is equivalent to $\frac{x}{x} \times 42$ , which simplifies to $1 \times 42$ (or just $42$ ).
Thus, the equation becomes: $42 = 12 x$
To find x, divide both sides by 12: $\frac{42}{12} = \frac{12 x}{12}$
Which gives, after simplification: $3.5 = x$ (or $x = 3.5$ )

So, if the dividend is 42 and the quotient is 12, the divisor is 3.5.