Question 417573
This is a linear equation of two unknowns as a result have an infinity  solutions
e.g. all real numbers with sum 5; (0,5), (1,4),(-2, 7),(-7,12), e.c.t.
Its graph is an line who all points on line are solutions for x+y=5.

{{{graph( 400, 400, -10, 10, -10, 10, 5-x)}}}