Divide the difference by the previous years total sales. For example if you sold 10000 worth of widgets last year and sales increased to 15000 worth this year you would calculate the variance as follows. The formula for calculating change is new value old value old value.
05 05 increase in employee cost.
The formula for calculating change is new value old value old value. Last year you sold 110. You sold 5 more paintings this year. For example this year you sold 115 paintings.