sum of array values...?

Hi ,I am new in Perl ,and I have to make 1 script related to
I have a for loop

for my $j(0..$#exons)
print "Length of value-",$exons[$j],"\n\n";
now whatever values are this loop is giving ,I have to get addition of
that all values and how many values it has?

Like if values are
Length of value-50
Length of value-500
Length of value-100

Output - Sum of Values-650
No. of value -3

How I can get it ? Thanks.