3.
var a,b,c:real;
begin
readln(a,b,c);
if (a=b) and (a=c) and (c=b) then writeln('равностороний')
else writeln('не равностороний')
end.
4.
var x,f:real;
begin
readln(x);
if x<=7 then f:=-3*x+9<br>else f:=1/(x-7);
writeln(f)
end.
5.
var a,b,c,s:real;
begin
readln(a,b,c);
s:=0;
if a>0 then s:=s+a;
if b>0 then s:=s+b;
if c>0 then s:=s+c;
writeln(s)
end.