SQL Syntax To Sum Fields From Two SQL Statements

I have two SQL statements that return sum(pcs) and sum(amt) from two differnt conditions. How do I get a total sum of pcs and amt from these two SQL went I union them?

SQL1: return columns value, SUM(pcs), SUM(amt) where amt is value*pcs

$2 , 4pcs, $8
$5, 5pcs, $25

SQL2: return similar columns value, SUM(pcs), SUM(amt) FROM another condition giving:

$2, 3pcs, $6
$5, 1pc, $5

If I use (SQL1 union SQL 2), I get

$2 , 4pcs, $8
$2, 3pcs, $6
$5, 5pcs, $25
$5, 1pc, $5

I want to get the final result as:

$2, 7pcs, $14
$5, 6pcs, $30

How to write the SQL statement to get the result? OR it is not possible at all?

Vincent