solve 0.25 = a + b + c + d, 0.45 = a + 1.5b + 2.25c + 3.375d, 0.8 = a + 1.7b + 2.89c + 4.913d, 1 = a + 2b + 4c + 8d

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.