To cube something means to take it by 3, when used in the sentance, 3 cubed it refers to 3^3 power which means 3*3*3 which equals 21. In this context I'm guessing that they mean 50^3 which would be $125,000.
Hope this helps!=)
It would be equivalent to x=8
If you divide 21/49 by 7 you get 3/7
A person drives 500 miles in 5 hours.