Math through the years

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?

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?

Math In 1970: A logger sells a truckload of lumber for $100. His cost of production is $80. Did he make a profit?

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.

Math In 1990: By cutting down beautiful forest trees, the logger makes $20. What do you think of this way of making a living? Topic for class participation after answering the question: How did the forest birds and squirrels feel as the logger cut down the trees. (There are no wrong answers.)

Math In 2005: Un hachero vende una carretada de maderapara $100. El costo de la producciones es $80.