Dominck, there is no mathematics in reading your hydrometer for getting a SG reading. If you look at the top of your Hydrometer scale you will see it starts at .990. That is basically as dry(fully fermented) as a wine get. The scale then goes up in value and hits 1.000 and then you will just add the decimal to it. It other words you were reading 80 on your wine which is 1.080. If it were a Port wine which has more alcohol you will notice that the scale keeps going until it reaches 1.100, after that it would read 1.110, 1.120 and so on. At 1.080 and you probably have started fermenting so you are right in the ball park with your wine. Right that # down so when you are finished fermenting you have a number subtract the lower SG(finished Fermentation) from. When this wine is done you will have a SG somewhere around 0.994. You will take the Starting SG of 1.080 and subtract the fin. SG of 0.994 and get the answer 0.086. You then multiply that # by 131.4 and this # 11.30 is your abv of your wine. In other words your wine has a proof of 22.6 Hope that helps you understand. I copied and edited a picture for you to better understand. The liquid level is reading at 1.071 but I have drawn an arrow to where the liquid level would be on your batch.
Also, when taking an SG reading there is a chart that should have come in the tube with your hydrometer that tells you how much to adjust for different temps. In example your hydrometer is calibrated to read correctly at 60* and your wine was most likely at around 75* when you added the yeast and took your 1st reading. At 75* you would have to .001 to your reading which would give you a reading of 1.081.If you didnt get a chart with your hydrometer here is 1 for you.
<a name="Hydrometer_Temperature">
Hydrometer
Temperature
Correction Table</font></a></font>
</font>
<table ="../s_B/bkgd-wmarb.jpg" border="1" width="600">
<t><tr>
<td align="center" width="50%">Degrees Fahrenheit</font></td>
<td align="center" width="50%">Adjustment to
Reading</font></td>
</tr>
<tr>
<td align="center" width="50%">40</td>
<td align="center" width="50%">Subtract .002</td>
</tr>
<tr>
<td align="center" width="50%">50</td>
<td align="center" width="50%">Subtract .001</td>
</tr>
<tr>
<td align="center" width="50%">60</td>
<td align="center" width="50%">CORRECT</font></td>
</tr>
<tr>
<td align="center" width="50%">70</td>
<td align="center" width="50%">Add .001</td>
</tr>
<tr>
<td align="center" width="50%">80</td>
<td align="center" width="50%">Add .002</td>
</tr>
<tr>
<td align="center" width="50%">90</td>
<td align="center" width="50%">Add .004</td>
</tr>
<tr>
<td align="center" width="50%">100</td>
<td align="center" width="50%">Add .005</td>
</tr>
<tr>
<td align="center" width="50%">110</td>
<td align="center" width="50%">Add .007</td>
</tr>
<tr>
<td align="center" width="50%">120</td>
<td align="center" width="50%">Add .008</td>
</tr>
<tr>
<td align="center" width="50%">130</td>
<td align="center" width="50%">Add .010</td>
</tr>
<tr>
<td align="center" width="50%">140</td>
<td align="center" width="50%">Add .013</td>
</tr>
<tr>
<td align="center" width="50%">150</td>
<td align="center" width="50%">Add .015</td></tr></t></table></font>
Edited by: wade