Solution

(a-8)/(b-8) = 1/2= 6/12 = (a-8+6)/(b-8+12) = (a-2)/b+4) = 1/2 ……(1)

(b+4)/(d+4) = 2/3……..(2)

(1)*(2)

(a-2)/(d+4) = 1/3

no applying componendo

(a+d+2)/(d+4) = 4/3            (also given (a+d)/2 = 27….(a+d) = 54)        

So 56/(d+4) = 4/3

d+4  = 42

d = 28