What is −2√20 − √125 in simplest radical form?

Can someone me my sister? she is in third grade. 50 points and brainlist! ones that are not answered. plz and thx!

50 ! pls ! 12.  building codes regulate the steepness of stairs. homes must have steps that are at least 13 inches wide for each 8 inches that they rise.

a. discuss how to find the slope of the stairs.
b. describe how changing the width or height affects the steepness of the stairs.

If you answer right ill give brainliest, : )