my $A = 250; # Pizza price
my $B = 300; # Selling price
my $C = $B - $A; # Difference
print "A = $A \n B = $B \n C = $C \n";
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Good news - Perl actually allows variable names with more than one character in them. This means that you no longer have to remember what $B is supposed to represent. Instead you can give that variable a meaningful name.

my $cost_price  = 250;
my $sale_price  = 300;
my $profit      = $sale_price - $cost_price;

print "Make them for $cost_price\nSell them for $sale_price\nMake $pro
+fit on each\n";
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Addendum: There is, as with most things, a happy medium.