query problem

Hello everyone, Good day! Could anyone help me translate this query in Microsoft Access to Postgresql. I'm having a difficulty. Pls...

Query1:
SELECT items.description, Sum(supplieditems.qty) AS SumOfqty
FROM items INNER JOIN supplieditems ON items.itemno = supplieditems.itemno
GROUP BY items.description;

Query2:
SELECT [items].[description], Sum([customer].[qty]) AS SumOfqty
FROM (items INNER JOIN OtherItem ON [items].[itemno]=[OtherItem].[Itemno]) INNER JOIN customer ON [OtherItem].[Itemno]=[customer].[itemcode]
GROUP BY [items].[description];

Query3:
SELECT [Query1].[SumOfqty], [Query2].[SumOfqty], [Query1]![SumOfqty]-[Query2]![SumOfqty] AS remain
FROM Query1, Query2;

I have translated Query1 and Query2 in POSTGRESQL but I don't know how to implement Query3.