Evaluating Expressions:
If you need to evaluate an expression, just replace the variable (the letter) with the number given.
Here are some examples:
Evaluate: 3a + 3b if a=2 and b=6
3(2) +3(6)= 6 + 18= 24
Evaluate: 2y-5t-7v if y=1, t=6, v=-1
2(1)-5(6)-7(-1)= -21