f(a) = (2^0 + 2^1 + 2^2)*m
= 2b = 2^5*s
7m=32s

m=32 , s=7

f(b) = (2^0 + 2^1 + 2^2 + 2^3 + 2^4)*n
= 2a = 2^3*r
31n = 8r

n=8 , r=31

a = 31*2^2 , b = 7*2^4