Respuesta :

Answer:The horizontal value in a pair of coordinates: how far along the point is. The X Coordinate is always written first in an ordered pair of coordinates (x,y), such as (12,5). In this example, the value "12" is the X Coordinate. Also called "Abscissa" See: Coordinates.

Answer:

x = 8

Step-by-step explanation:

Vertical angles are congruent.

21x-17 = 15x+31

6x-17 = 31

6x = 48

x = 8