What is x when 78 divided by x equals 42?

To find the answer, just divide the dividend by the quotient: 78 ÷ 42 = 1.8571428571429

To prove this, let's compute 78 divided by 1.8571428571429: $\frac{78}{1.8571428571429} = 42$

How does it work?

Asking what the value of x could be when 78 divided by x gives a result of 42, is equivalent to solving the following equation:

$\frac{78}{x} = 42$

Multiply both sides by x: $\frac{78 x}{x} = 42 x$
$\frac{78 x}{x}$ is equivalent to $\frac{x}{x} \times 78$ , which simplifies to $1 \times 78$ (or just $78$ ).
Thus, the equation becomes: $78 = 42 x$
To find x, divide both sides by 42: $\frac{78}{42} = \frac{42 x}{42}$
Which gives, after simplification: $1.8571428571429 = x$ (or $x = 1.8571428571429$ )

So, if the dividend is 78 and the quotient is 42, the divisor is 1.8571428571429.