Changing out a 1955 Toilet

I am going to try and help my elderly Aunt by changing out her old leaking toilet and installing a new one. The old one was from 1955
I noticed that the old toilet has 4 floor bolts, 2 on each side.
This stymies me, what do I have to do to install a new one with only the 2 floor bolts in the middle of each side.
HELP.....

The back ones are the ones that count.
Measure from the the back wall, to the center of the back bolts.
That should be your "rough-in" measurement.

You can throw away the front bolts when the bowl is removed.