say the body has a velocity of um/s when it's 4.5m above the tower when the body reaches the highest point n comes to the same position then it will have the same vel of u m/s.further when the body descends 9m then it has a vel of 2u m/s (given)

           4u^2-u^2=2g9=>u=14(0.3) ^1/2=>

   when the body is at 4.5 abv the tower it has a vel of u=>from there it reaches a height(h) of u^2/2g

       =>h=3=>it is 40+4.5+3=47.5m abv ground

      hope u got it rate me if u satisfied