Sinker Redwood

Sinker Redwood
These are the most difficult problems of density in the world! Oh please, please, help me?

9.09 g piece of wood is fixed to a 22.8 g of lead ballast. Underwater the couple has an apparent mass of 9.69 g. If lead is a black mass of 20.89 g of what to sample density Redwood? Theres 8 more ..... if u teach me to do what I can do the rest. U would save my life

Density = mass in air / (mass in air - mass in water) = (of Lead) 22.8 / 22.8 to 20.89 = 11.94 = (Lead + wood) 31.89 / 31.89 to 9.69 = 1.44, a ratio of 22.8 / 31.89 of the two elements combined have a density of 11.94, a ratio of 9.09 / 31.89 combined the two elements has a density of x 31.89 / 31.89 for the two elements combined with a density of 1.44 therefore 0.715 / 11.94 + 0.285 / x = 1 / 1.44 thus 1.44 (0.715 / 11.94 + 0.285 / x) = 1 therefore 1.44 x 0.06 + 0.285 / x = 1 for both 0.285 / 0.91 x = 0.91 x = 0.285 so as the density of wood = 0.285 / 0.91 = 0.313 g / cm ^ 3