Design a differential op amp (subtractor)
1) For a "normal" op amp, start with R1 and R2 at 10k. This will produce currents of about 1 mA for 10 volt differences, and that's a perfectly normal current. Unless you also want super-low amplifier current, as you might well do if you're using batteries. And 9 volts is a standard battery voltage.

2) Use the input voltages for your two stated conditions. Find the output difference and divide by the input difference, and that's your gain.

3) Now you have to produce your input offset. Given your input conditions, this should be easy.

4) Finally, a caution. You should note that, for V+ equals 9 volts, and V- equals zero, most real op amps will not produce an output swing from zero to 9 volts. Those that do are called rail-to-rail output amps, and even those don't do well at each extreme if called on to produce much current.