Which option best shows X < -15

Please explain as well, thanks! :)

The line going to the left aka the negative side!

X < -15 means X is less than -15

The line's purpose is to to show the possibilities of X.

So all the numbers lower than -15 are all possibilities of X. (Example: -16, -17 or -20 would be a possibilty of X because they are less than -15!)

Anything going above -15 is not a possibility of X (Example: -14, -13, or 2 are not possibilities of X as they are greater than -15!)

1 number

if we use a graphing calculator, there is only one such number that satisfies the conclusion of the mean value theorem, that is, a number such that

where the right-hand side is the average rate of change of f on the interval [0.5,0.75], which is the slope of the secant line.

in the attached graph, the black line is the secant line which has its slope as the average rate of change of f on [0.5,0.75], while the orange line is the only tangent line to the graph of f in the interval that satisfies the mvt conclusion.