The sun is located

in the central core of the milky way galaxy
in the bar of the milky way
in an arm about 25% of the distance from the center of the milky way to its outer edge
in an arm about 75% of the distance from the center of the milky way to its outer edge

a. the production of carbon dioxide through the process of photosynthesis

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)