GFCI: both load and line have voltage
The black with the 117 ish and the white from that same cable go to the line side then the black with 30 and that white go to the load. Make sure to get the correct black and white wires coming from the same cable on each side this configuration will provide GFCI protection to everything down from the GFCI connect the bare copper to the green ground screw.
The 30 ish in almost every case phantom voltage it has no real potential and is induced voltage because the line wires are running with the load , nothing to worry about. This is how transformers work but they have lots of wire in close contact so you get the current there but not here.
Edited ;
I misread the voltages thanks to doxylover, the white wire that appeared grounded and the black in cable that it is with is probably the line side   The black and white on the load showing a voltage is still phantom, if we want to verify this the safest way is to tie the 2 whites together then with the blacks not connected plug in a load down stream the whites instantly go to ground when connected and since the 1 phantom black is now connected to a load the voltage will dive. If a hair dryer or other large resistive device is used the voltage on the load black will be close to zero but maybe a few volts. The line side black won’t change still 117 and the white that that black comes in with is the proper neutral for the line side.