In algebra, letters are used when numbers are not known.
Algebraic terms, like or , leave the multiplication signs out. So rather than , write , and rather than write .
A string of numbers and letters joined together by mathematical operations such as and is called an algebraic expression, for example
Suppose that is the cost of child admission and is the cost of adult admission to the zoo:
a) How much does it cost for the Khan family of children and adults to visit the zoo?
b) Write an algebraic expression for the cost for the Norman family of children and adults to visit the zoo.
a) Cost for children =
Cost for adults =