this is not a complex problem you might think it is. First I would mark time as x and wages as y. make a long fraction line, on the top you place ysub 1 subtract by y sub2. under the line is the same thing but with x. for example on the top 0-1, the buttom of the line 0-9. you would get negative 1 over negative 9. divide negative 1 and negative 9. if comes up a decimal leave it as a fraction.