Explanation

CH₃MgBr is a Grignard reagent (a source of CH₃⁻ nucleophile).

CH₃O is shorthand for methanal (HCHO) or a methoxy group, depending on context.

Assuming the intended compound is an ester like methyl formate (HCOOCH₃), then:

CH₃MgBr reacts with an ester in two steps:

1. First addition forms a ketone.

2. The second addition gives a tertiary alcohol after hydrolysis.

So, the final product is a tertiary (3°) alcohol.