проверте, разве не так

uses crt;
const n=12;
var w,x,y,z:array[1..n]of integer;


procedure Init(var a:array[1..n] of integer);
var i:integer;
begin
for i:=1 to n do
begin
a[i]:=random(10)-random(7);
write(a[i]:3);
end;
writeln;
end;
function p(var a:array[1..n] of integer):longint;
var i:integer;
s1:longint;
begin
s1:=1;
for i:=1 to n do
if a[i]>0 then s1:=s1*a[i];
p:=s1;
end;

function s(var a:array[1..n] of integer):longint;
var i:integer;
s1:longint;
begin
s1:=0;
for i:=1 to n do
if a[i]>0 then s1:=s1+a[i];
s:=s1;
end;

begin
clrscr;
Init(w);
Init(x);
Init(y);
Init(z);
writeln((p(w)+p(x))/(s(y)+s(z)):8:4);
end.