Decide whether the following statements are true or false.$$

Deborah owed Colleen $$500,$ and the debt was past due.$$ Colleen said, $$If you pay me $$300$ now, I$$ll forget the other $$200.$ Deborah paid Colleen the $$300$ and owes no more.

Bank offered a $$1000$ reward to anyone who helped the police catch two bank robbers.$$ Sally, an employee of the bank, did help in such an instance.$$ She is entitled to the $$1000.$

Coal$-$fired Electric Company agrees to $$buy all the coal it needs$$ from Coal Company for five years.$$ Since Electric Company did not necessarily agree to buy any coal at all, it has made an illusory promise unsupported by any consideration and can quit its relationship with Coal Company without consequence

William billed Denise $$200$ for cleaning her computer of viruses, but Denise complained: $$My computer is still behaving weirdly.$$ It turned out that William had missed some viruses in hidden files.$$ Denise said, $$I$$m paying you only $$100$ by check marked $$Paid in Full.$$ William cashed the check and then sent Denise a statement showing $$100$ still owing.$$ Denise owes the other $$100.$