It's an iffy situation. It's cheap, but it might blow your analog input, because your analog input circuit is likely to 'see' 20 volts, not 10 volts:
You want to see from a 10 volts range which is 10-20 volts with respect to the source's low side. Whether your analog input will do that depends on how much common mode it can tolerate and how high it can float above ground.
A couple of 100k ohm resistors in series will provide a reasonable impedance to the source, and will load your analog input slightly, but scaling can correct for the error.
The problem is that the point labeled a (negative terminal at source) is probably grounded somewhere, so the your analog input will likely see the voltage with respect to ground, not with respect to its own (-) terminal.
Your low side is elevated above the source's negative.
Some AI's can't take much common mode voltage. Some will saturate so the signal looks full scale up or down and not be damaged, but others can be damaged by excessive common mode.
If your analog input is single ended, do not try this.
If your analog input is differential, it might handle it.