PLEASE HELP THIS IS DUE IN A COUPLE MINS what number must you subtract from -13 to get a difference of 0? so i know the answer to this part; its -13 but i dont know how i got that answer like i dont know how to explain it please help :sob:

Organisms that live in the alpine and taiga biomes have developed unique adaptations that aid in their survival. the douglas-fir is a conifer tree that grows in the taiga biome. it has an average height of about 70 feet, and its wood is an important source of lumber.

Mary works for a company that ships packages and must measure the size of each box that needs to be shipped. mary measures a box and finds the length is 7 inches, the width is 14 inches, and the height is 15 inches. what is the volume of the box? [type your answer as a number.]

If the measure of angle 1 is 110 degrees and the measure of angle 3 is (2 x+10 degree), what is the value of x?