How would I solve for the molar mass of Lactic Acid?

This is a question from my homework, this is my first year of chemistry in high school, and I didn't understand the way I was taught. Q: Lactic acid, a chemical responsible for muscle fatigue, is a monoprotic acid. When 0.578 g of lactic acid is titrated with 0.206 M NaOH, a volume of 31.11 mL of NaOH is... show more This is a question from my homework, this is my first year of chemistry in high school, and I didn't understand the way I was taught.

Q: Lactic acid, a chemical responsible for muscle fatigue, is a monoprotic acid. When 0.578 g of lactic acid is titrated with 0.206 M NaOH, a volume of 31.11 mL of NaOH is used. What is the molar mass of lactic acid?
HA + NaOH → NaA + H2O
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