What exactly is your question?
Let "x" be a substitute for "a number"
1/3(x)=x-12 Multiply by 3
x=3x-36 Get n onto the same side of the equation
2x=36 Divide by 2
x=18
That's your answer.
The square root of 58 is around 7.6
The entire number is, 7.61577310586...
"Quantitative" information is information that consists of numbers
and tells you the measure (quantity) of something.
The cost, mileage, and weight of the car are all quantitative items.
The model of the car may have numbers in it, but it doesn't tell
the measure of anything. It isn't quantitative data.