The price of a model M camera is $209 and the price of a special lens is $69. When the camera and lens are purchased together, the price is $239. The amount saved by purchasing the camera and lens together is approximately what percent of the total price of the camera and lens when purchased separately?
For estimates, just round the numbers to 210, 70, and 240.
Thus, Savings = (210 + 70) - (240) = 40
Amount Saved/Total Cost = 40/280 = 1/7, then some quick division gives you an estimate of 14%.