Say you have an accelerometer that outputs 1.8V @ 0g with a variation of +/-0.95V for a full scale range of +/-50g.
This circuit outputs 0V when the accelerometer measures -20g and 10V when it measures +20g.
Due to lack of precision with the resistors we can get the exact outputs. This could be fixxed with potentiometers (and/or a more involved design) but im too lazy :p