A variable is: A symbol or letter that can be used to represent an unknown value
coffee …$2.00
tea …$3.50
Juice …$1.25
4 coffees and two teas calculate
4c + 2t = $15.00
3x + 2 cannot be determined
evaluate: find a value for an expression by substituting a value in for your variable
when x = -2, 3x + 2 = -4
care order of operation
7 + 3(x-2) when x=4
