Plants use the process of __ to remove carbon dioxide from the air.

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.

: -)

a compound light microscope is used to magnify objects in steps.  

hope it