MQ10 --- Percentage

Let Ao and An be the old and new surface area respectively
Vo and Vn be the old and new volume respectively
M be the mass

Since An = (1+125%)Ao
> An/Ao = 2.25

Therefore, Vn/Vo = [ sqroot(An/Ao) ] ^3
> Vn = [(2.25) ^ (3/2)] * Vo

New density
= M/Vn
= M / [(2.25) ^ (3/2)] * Vo
= (M/Vo) / [(2.25) ^ (3/2)]

Percentage change of density
= {(M/Vo) / [(2.25) ^ (3/2)] - M/Vo} / M/Vo
= {1/[(2.25) ^ (3/2)] - 1} / 1
= -70.37%