First compute h9(x)
Given: hn(x)=gn(x) , g(x)= x+1
g2(x)= g(g(x)) = g(x+1)=(x+1)+1 =x + 2*1
g3(x)= g(g(g(x))) = g(g2(x))=g(x+2)= (x+2)+1 = x+3 = x+ 3*1
Seeing this pattern we can infer that g9(x) = x+ 9*1=x +9
So, h9(x)=g9(x)=x+9
Now we have to compute h98(x) where x=72
h91(x) = x+9
h92(x) = h9(h9(x)) = h9(x+9) = (x+9) +9 = x+2*9
h93(x) = h9(h9(h9(x))) = h9(h92(x))= h9(x+2*9) = (x+2*9) +9 = x+3*9
Again following the same pattern we can conclude that
h98(x) = x +8*9 =x+72
Put x=72 , it becomes 72+72=144