A lady bought 40 pencils with the unit price of $1/pencil. She bought 60 pens with the
unit price of $2/pen. There are 100 boxes with the unit price of $3/box. Then she put
one pencil and one pen into one box. Then she sold the box for $10/box and as many as
possible. For the remaining stuffs, she sold $3/pencil, $4/pen, and $0.5/box out. How
much profit can she make?
答案：50.0