Solution - Simplification or other simple results

Step  1  :

 1.1     10 = 2•5

(10)⁶ = (2•5)⁶ = 2⁶ • 5⁶

Equation at the end of step  1  :

  15 • (26•56)

Step  2  :

Multiplying exponents :

 2.1    5¹  multiplied by  5⁶   = 5^{(1 + 6)} = 5⁷

Final result :

  (3•57•26)