Let "a number" be signified by x.
"A number" to the 11th power,
x^11
divided by "the same number" to the 8th power,
x^11 / x^8
equals 216,
x^11 / x^8 = 216
Apply your exponent rule, division to subtraction,
x^(11-8) = 216
x^3 = 216
"the number" is being raised to the third power.
To isolate our number, x, we'll apply the inverse of raising to a power:
Taking a third root (or applying a 1/3 power).
[tex]\large\rm x = \sqrt[3]{216}[/tex]
and simplify,
x= 6
