your friend works part time for a newspaper publisher and earns a commision of $1.50 for each 3-line classified ad he sells and $2.25 for each 5-line classified ad he sells. During a certain week he made a total of 80 sales and earned $157.50. How many 3-line classified ads did he sell?

He sold 30 3-line classified ads

Step-by-step explanation:

Commission for sales of each 3-line classified ad = $1.50

Commission for sales of each 5-line classified ad = $2.25

Total number of ads sold = 80

Earnings = $157.50

Since, the commission for the sales of 5-line classified ad is greater than the commission for the sales of 3-line classified ad, he sold 50 5-classified ads and 30 3-classified ads

Commission for 50 5-classified ads = 50*$2.25 = $112.5

Commission for 30 3-line classified ads = 30*$1.50 = $45

Total commission = $112.5+$45 = $157.50