It is choice (D)
Let's set that unknown number to x.
The first step is the difference of 3 times a number and 15 --> 3x - 15
That is no less than the square of the number '[tex]\geq[/tex] [tex]x^{2}[/tex]'
Now combine them [tex]3x - 15 \geq x^2[/tex]
Hope that helped!
