HNMR of the starting material and product of ethyl 3-hydroxybutanoate please draw both structures for all distinct type of protons (with different

HNMR of the starting material and product of ethyl 3-hydroxybutanoate

1. please draw both structures for all distinct type of protons (with different letters for the product and starting material) 
2. what is the molar ratio of the starting material and product. calculate the mass % of ethyl 3-hydroxybutanoate(product)?
3. what was the concentration of ethyl 3-hyroxybutanoate that dissolved in methanol to put into the polarimeter?

3.4 g(9.00 mmol) NaBH4

1.4 g (9.28 mmol) tartaric acid

0.310 g (2.30 mmol) ethylacetoacetate

0.036 g ethyl 3-hyroxybutanoate

polarimetry:

2.00 ml methanol

reading: -0.035

Thank you