I need help on my chem lab... I need to give you background info so you know how to help me..

Question

Data Sheet:
Specific gravity of distilled water
Temp of distilled water = 20 C
Specific gravity: 1.0000 or 1.000 (according to hydrometer used)
sugar solution 1 : mass 18.01 g volume 500 ml specific gravity 1.014
sugar solution 2 36.01g 500 ml 1.027 SG
sugar solution 3: 52.98 g 500 ml 1.039 sg

specific gravity of regular coke: 1.050
of gatorade: 1.025

1. Calculate the density of distilled water used.
Answer I got: specific gravity is 1.000
density is SG*1000kg/m^3 = 1*1000 kg/m^3 or just 1g/cm^3

2. calculate the concentration in % of standard sugar solutions
Answer I got:
sugar solution 1 (18.01/500)=.036*100=3.6%
sugar solution 2
(36.01/500) = 0.072*100= 7.2%
sugar solution 3
(52.98/500) = 0.106*100= 10.6%

**** Help here***
Using information (sugar and serving size) on nutrition label of each drink, determine the concentration of sugar in each drink. Show calculations?
Coke 20 oz = 65g sugar per 591 ml
So, would I first find the 1000ml?? do I calculate 591/1000 * 65g = 38.4%?? or is it just 65g/591 = 11%?? confused how to work this

***** Help with how to work this****

Calculate the absolute errors of measured sugar concentrations by using the values determined in the previous problem as reference values.....

How do I calculate this ??? Help!!!