3.) A parcel of joint tenancy real property owned by Parent and Child was worth $25,000 at its acquisition in 1995 and $50,000 at decedent's death. What is the result under Section 2040 in the following situations?

a.) Parent paid the full $25,000 purchase price; Parent predeceases Child.

b.) Parent paid the full $25,000 purchase price; Child predeceases the Parent.

c.) Parent and Child each contributed $12,500 of the purchase price; Parent predeceases Child.

d.) Parent contributed $15,000 of the purchase price and Child contributed $10,000; Parent predeceases Child.

e.) Grandparent devised the property to Parent and Child as joint tenants; Parent predeceases Child.

f.) What would the results be in questions (3)(a), (3)(b), and (3)(d) above, if joint tenants were spouses, not Parent and Child?