The ratio x/y on completion of the reaction is 

Glyoxylic acid has the structure: OHC-COOH (an aldehyde and a carboxylic acid group).

When glyoxylic acid reacts with excess MeMgBr (Grignard reagent):

The first equivalent of MeMgBr reacts with the acidic -COOH group (acid-base reaction):

$$-\text{COOH} + \text{CH}_3\text{MgBr} \rightarrow -\text{COO}^-\text{MgBr}^+ + \text{CH}_4$$

The second equivalent of MeMgBr performs nucleophilic addition to the -CHO group:

$$-\text{CHO} + \text{CH}_3\text{MgBr} \rightarrow -\text{CH(OMgBr)CH}_3$$

After hydrolysis with H$$_3$$O$$^+$$, the product is 2-hydroxypropionic acid (lactic acid type).

So for $$y$$ moles of glyoxylic acid, $$x = 2y$$ moles of MeMgBr are needed.

$$\frac{x}{y} = 2$$