What is x when 77 divided by x equals 15?

To find the answer, just divide the dividend by the quotient: 77 ÷ 15 = 5.1333333333333

To prove this, let's compute 77 divided by 5.1333333333333: $\frac{77}{5.1333333333333} = 15$

How does it work?

Asking what the value of x could be when 77 divided by x gives a result of 15, is equivalent to solving the following equation:

$\frac{77}{x} = 15$

Multiply both sides by x: $\frac{77 x}{x} = 15 x$
$\frac{77 x}{x}$ is equivalent to $\frac{x}{x} \times 77$ , which simplifies to $1 \times 77$ (or just $77$ ).
Thus, the equation becomes: $77 = 15 x$
To find x, divide both sides by 15: $\frac{77}{15} = \frac{15 x}{15}$
Which gives, after simplification: $5.1333333333333 = x$ (or $x = 5.1333333333333$ )

So, if the dividend is 77 and the quotient is 15, the divisor is 5.1333333333333.