Matt gets a $1,000 commission on a big sale. This commission alone raises his average commission by $150. If Matt's new average commission is $550, how many sales has Matt made?
Choose the correct answer:
A) 3 B) 4 C) 5 D) 6 E) 7
Let, Average Commission = x   No. of items sold = y   Total Commission = xy   New Commission = xy+1000   New Average = (xy+1000) / (y+1) = 150+x   i.e. (xy+1000) = (y+1)* (150+x)   i.e. (xy+1000) = (xy+x+150y+150)   i.e. (850) = (x+150y)   New Commission = 550 = 150+x   i.e. x=400   i.e. y = 3   New Sales = y+1 = 4   Answer: option 4
<result>B</result>
Matt gets a $1,000 commission on a big sale. This commission alone raises his average commission by $150. If Matt's new average commission is $550, how many sales has Matt made?