What is x when 78 divided by x equals 4?

To find the answer, just divide the dividend by the quotient: 78 ÷ 4 = 19.5

To prove this, let's compute 78 divided by 19.5: $\frac{78}{19.5} = 4$

How does it work?

Asking what the value of x could be when 78 divided by x gives a result of 4, is equivalent to solving the following equation:

$\frac{78}{x} = 4$

Multiply both sides by x: $\frac{78 x}{x} = 4 x$
$\frac{78 x}{x}$ is equivalent to $\frac{x}{x} \times 78$ , which simplifies to $1 \times 78$ (or just $78$ ).
Thus, the equation becomes: $78 = 4 x$
To find x, divide both sides by 4: $\frac{78}{4} = \frac{4 x}{4}$
Which gives, after simplification: $19.5 = x$ (or $x = 19.5$ )

So, if the dividend is 78 and the quotient is 4, the divisor is 19.5.