pH calculation from 0 .1M solution of sodium carbonate

Calculate the pH of a 𝟎.𝟏 M solution of sodium carbonate (Na𝟐CO𝟑), given the following information: 𝑲𝒃𝟏 = 𝟐. 𝟏 × 𝟏𝟎−𝟒 , 𝑲𝒃𝟐 = 𝟐. 𝟐 × 𝟏𝟎−𝟖