Floyd is an aspiring music artist. He has a record contract that pays him a base rate of $ 2 0 0 $200dollar sign, 200 a month and an additional $ 1 2 $12dollar sign, 12 for each album that he sells. Last month he earned a total of $ 6 4 4 $644dollar sign, 644. Write an equation to determine the number of albums ( a ) (a)left parenthesis, a, right parenthesis Floyd sold last month. Find the number of albums Floyd sold last month.