Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
solve (n-1)d = 40,\frac{n}{2}\left[2\times 100 + (n-1)d\right] = 180(n-2)
solve (n-1)d = 40,\frac{n}{2}\left[2\times 100 + (n-1)d\right] = 180(n-2)
Natural Language
Math Input
Extended Keyboard
