For $1977.60 he buys as many acres as $3.09 is contained times in
$1977.60, or 640. Hence, he buys 640 acres.
SELLING PROBLEM: My agent _sells_ 360 pounds of butter for me at 20
cents. He pays $4.20 freight charges and $9.60 for storage. His
commission is 5%. What does he send me?