What is the mass of the beaker and fluid on the triple beam balance? A) 10.21 g
B) 200.11 g
C) 210.91 g
D) 211.91 g

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?