Ответ:
PascalABC.NET 3.5.1 + .NET Framework 4.7.1
#1
begin
var A := ReadSeqIntegerWhile(p -> p <> 0).ToList;
A.Where(p -> (p < 0) and (abs(p) mod 10 = 1)).Average.Println;
end.
#2
begin
var A := ReadArrInteger(ReadInteger());
var max_even := A.Where(p->p mod 2 = 0).Max;
var max_ind := A.IndexOf(max_even);
if max_ind = -1 then print('Нет') else print(max_ind+1);
end.
Объяснение: