Answer
The number we are looking for is $800$.
Work Step by Step
We first translate this statement into an algebraic equation:
"$120$ is" means "$120 = $."
"15% " can be translated into a decimal, which would be $0.15$.
"Of what number" means multiplying by $x$.
We now put the whole statement together into the following equation:
$$120 = 0.15x$$
We solve for $x$ by dividing each side by $0.15$:
$$x = 800$$
The number we are looking for is $800$.
