看到一个评论，分析为啥数学分数这么差，很搞笑。

This is what has happened to match teaching over the last few decades.....

Teaching math in 1960's
A logger sells a truckload of lumber for $100. His cost of production is 4/5 of the price. What is his profit ?

Teaching math in 1970's
A logger sells a truckload of lumber for $100. His cost of production is 4/5 of the price, or $80. What is his profit?

Teaching math in 1980's
A logger sells a truckload of lumber for $100. His cost of production is $80. Did he make a profit ?

Teaching math in 1990's
A logger sells a truckload of lumber for $100. His cost of production is $80 and his profit is $20. Your assignment: Underline the number 20.

Teaching math today
A logger cuts down a beautiful tree because he is selfish and inconsiderate and cares nothing for the habitat of animals or the preservation of our woodlands. He does this so he can make a profit of $20. What do you think of this way of making a living? Topic for class participation after answering the question: How did the birds and squirrels feel as the logger cut down their homes? (There are no wrong answers, and if you feel like crying, it's ok).