Mass of a tree in Oakland= 3 x 10^6 Kg
Mass of tree in Mapleville = 6 x 10^4 Kg
to find how many times the mass of tree in Oakland with the tree in mapleville,
Divide the mass of tree in Oakland by the mass of tree in Mapleville
So, The mass of tree in Oakland is 50 times
Answer : B) 50