II don't understand the solution provided, can you re explain in more details

1: Calculate the complexity of the following functions in terms of complete derivation of time omplexity T(n) and Big-Oh notation. [50 marks ] a) public int power(int a, int n){ //assume that n is a positive integer to calculate an if (n=0) return 1;//2[1] else if (n==1) return a;//1 from if +2[2] else return a power (a,n1);//2 from if and else +3+T(n1)[3] \} T(n)=5+T(n1)=5+5+T(n2)=5+5+5+T(n3)[4] Let k=3 when nk=1 recursivity stops and k=n1[1] T(n)=5k+T(1)=5n5+3=5n2[4] O(n)[15] For(I=0;I