Perhaps this is one of the reasons for the deterioration of standards since the 1940's.....

Last week I purchased a burger and fries at McDonalds for $3.58.The counter girl took my $4.00 and I pulled 8 cents from my pocket and gave it to her. She stood there, holding the nickel and 3 pennies. While looking at the screen on her register, I sensed her discomfort and tried to tell her to just give me two quarters, but she hailed the manager for help. While he tried to explain the transaction to her, she stood there and cried.
Why do I tell you this?
Because of the evolution in teaching math since the 1950s:
Teaching Math In 1950 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 1960 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 1970 A logger sells a truckload of lumber for $100. His cost of production is $80. Did he make a profit?
Teaching Math In 1980 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 In 1990 A logger cuts down a beautiful forest 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.)
Teaching Math In 2007 Un ranchero vende una carretera de madera para $100. El cuesto de la produccion era $80. Cuantos tortillas se puede comprar?