C I think sorry if I’m wrong
Answer:

Step-by-step explanation:

Sales increased 50% last year, from $5,000 to $10,000. When sales dropped from $10,000 to $5,000 this year, sales decreased 50%
first multiply the outside numbers by both the numbers in the ()
10xg=10g 10x5=50 2xg=2g 2x9=18
then combine like terms
10g+50=2g+18
8g=32
then divide
g=4