Algebra

Writing equations


Now, lets try writing out an equation with an example ...



If computers cost $a each & desks cost $b each, write down an expression for the total cost in dollars of 6 computers & 8 desks.

Well, the cost of 6 computers is just 6a ...
                                                                                   ... and the cost of 8 desks is 8b

So, the total cost of the computers & desks is:
                                  6a + 8b


and here's a more complicated example ...



We're told that ...

Bob thinks of a number
He then adds 6 to the number
He then multiplies it by 3
His answer is 30, what number did Bob think of?

Well, to answer this it's best to write it out as an equation.

So, Bob originally thought of the number 4!