0.031*(-886 + (-876))/2 *10 + 0.055*(-876 + (-866))/2 * 10 + 0.014*(-866 + (-856))/2 * 10

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.