Debbie owed Carlos $$50,000$ on a contract for the

purchase of $200$ air$-$conditioners on credit, the terms of

payment stating $$Payment due $60$ days after delivery.$$

Delivery was made on January $2.$ On March $10,$ Debbie

met Carlos and told him, $$I$$m sorry I missed out on paying

you what I owe you. Collections have been slow. If you

give me until May $1,$ I$$ll pay you what I owe plus interest

at $9\%.$ Carlos said, $$O$.$K$.$ I$$ll give you until May $1.$ On

March $15,$ Carlos changed his mind and sued Debbie for

$$50,000.$ Debbie contends that the debt is not due until

May $1.$ Is Debbie$$s contention valid? Explain.