What is x when 42 divided by x equals 39?

To find the answer, just divide the dividend by the quotient: 42 ÷ 39 = 1.0769230769231

To prove this, let's compute 42 divided by 1.0769230769231: $\frac{42}{1.0769230769231} = 39$

How does it work?

Asking what the value of x could be when 42 divided by x gives a result of 39, is equivalent to solving the following equation:

$\frac{42}{x} = 39$

Multiply both sides by x: $\frac{42 x}{x} = 39 x$
$\frac{42 x}{x}$ is equivalent to $\frac{x}{x} \times 42$ , which simplifies to $1 \times 42$ (or just $42$ ).
Thus, the equation becomes: $42 = 39 x$
To find x, divide both sides by 39: $\frac{42}{39} = \frac{39 x}{39}$
Which gives, after simplification: $1.0769230769231 = x$ (or $x = 1.0769230769231$ )

So, if the dividend is 42 and the quotient is 39, the divisor is 1.0769230769231.