let us suppose that during travelling 40m in last 2 sec its initial velocity was u.

then, ut+1/2gt^2=40 ( for last 2 sec)

 2u-19.6=40

u=29.8m/s

now considering from top to this position, u=0 and v=29.8m/s

then by v^2-u^2=2gh

29.8^2=2*9.8*h

h=45.3m

 so total height of tower=45.3+40= 85.30m