 ## Variables, Operators and Expressions

A variable is a letter that stands for a number. For example, when we used the letter "b" to stand for the
base of a triangle, we were using the variable b

An operator is add, subtract, multiply or divide.

Note: There are other operators
but we won't go into them now.

An expression puts variables together with constants and operators. For example, the expression for the area of a triangle is:
 ½ x b x h       or (b x h) / 2     or (b x h)       2

where: b = base and h = height

Usually, multiplication of 2 variables is shown without any operator, like this:

b h so, if b = 5 and h = 4 then b h = 5 x 4 = 20

Division is shown with a horizontal line, or a slash (/) or the divide symbol (÷):

b h = b h / 2 = b h ÷ 2
2
So... if you have 2 variables "a" and "b", then...
If a = 3 and b = 5, here are some expressions:

a + b = 3 + 5 = 8 a + 2b =
3 + 2 x 5 =
3 + 10 = 13 <= do the multiply first!
ab = 3 x 5 = 15
a - b =
3 - 5 = - 2 <= Remember your negative numbers!

5a = 5 x 3 = 15 = 3
b       5         5

 Now, here is a problem for you:    If a = 7 and b = 5, what is     (8a - 2b) / 2 = ______________