A variable is a letter, for example x, y or z, that represents
an unspecified number.
To evaluate an algebraic expression, you have to substitute a
number for each variable and perform the arithmetic operations. In
the example above, the variable x is equal to 6 since 6 + 6 =
If we know the value of our variables, we can replace the
variables with their values and then evaluate the expression.
Calculate the following expression for x=3 and z=2
Solution: Replace x with 3 and z with 2 to evaluate the
Video lesson: Evaluate the following expression
for x = 2, y = 5 and z = 4