If the sides of two cubes are in the ratio 3: 1 the ratio of their total surface area is?

A. 120, 40, 60 days
B. 120, 60, 80 days
C. 40, 30, 120 days
D. 30, 40, 60 days
Let a: be the time in which X & Y completes their work = 30 days
b: time in which Y & Z completes their work = 24 days
c: time in which X & Z completes their work = 40 days
X alone can complete the work in (2 * a * c) / (ab + bc – ac) days
= 2 * 30 * 24 * 40 / ((30 * 24) + (24 * 40) – (30 * 40)) = 120 days
Y alone can complete the work in 2 * a * b * c / (- ab + bc + ac) days
= 2 * 30 * 24 * 40 / (-(30 * 24) + (24 * 40) + (30 * 40)) = 40 days
Z alone can complete the work in 2 * a * b * c / (ab – bc + ac) days
= 2 * 30 * 24 * 40 / ((30 * 24) – (24 * 40) + (30 * 40))
= 60 days