Echo Systems has purchases of $251,400 and sales of $328,300 in May 2020. Select whether Echo Systems has a GST remittance payable or a GST refund receivable, and its amount. Your answer should be rounded to the nearest cent. Echo Systems has a of $ 0.00 Echo Systems has purchases of $251,400 and sales of $328,300 in May 2020. Select whether Echo Systems has a GST remittance payable or a GST refund receivable, and its amount. Your answer should be rounded to the nearest cent. Echo Systems has a of $ 0.00