Hold on, you don't have 7.5% yet. That scale on the hydrometer is "potential ABV" and I think it means more to the wine makers. What you want to pay attention to is the specific gravity scale, and remember to correct for temperature. Your hydrometer is calibrated to a particular temperature. Its written on it somewhere. Measure the specific gravity at that temperature, or use a correction calculator like this.
Write down your initial reading from a sample taken after
the wort has mixed thoroughly in the fermenter prior to pitching the yeast. This is your Original Gravity
. After fermentation has concluded in a couple of weeks, take another sample and remember to correct for temperature. If consecutive readings over several days show no change, this is your Final Gravity
. Plug both of them into a calculator like this
That will give you your ABV. For instance you are starting at 1.060 and lets say you ferment out to 1.012, your ABV would be 6.3%.