Solution - Simplification or other simple results

Step  1  :

 1.1     9 = 32

(9)² = (3²)² = 3⁴

Equation at the end of step  1  :

  ((152) +  (112)) +  34

Step  2  :

Equation at the end of step  2  :

  ((152) +  112) +  34

Step  3  :

 3.1     15 = 3•5

(15)² = (3•5)² = 3² • 5²

Equation at the end of step  3  :

  ((32•52) +  112) +  34

Step  4  :

Final result :

  427