Which would cause the weather to change from moist to dry? A. an increase in air pressure
B. a decrease in humidity
C. an increase in air temperature
D. a decrease in cloud cover

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.

: -)

her next move would be to use agarose gel electrophoresis to separate the dna molecules of varying length and create a dna fingerprint.