Dodit is a father with 4 children, consisting of 2 grown sons and 2 daughters. However, after the death of his wife, Mr. Dodit remarried a widow with 1 child. From the results of his second marriage, Mr. Dodit was blessed with one daughter. After Mr. Dodit's death, it was discovered that he had gifted a pond area of 1 hectare to his first child, this was proven by a deed of gift that had been made before a notary. Meanwhile, it is known that Mr Dodit left behind 4 houses with an estimated price of IDR 800,000,000, 4 cars with an estimated total price of IDR 800,000,000.

a. Who has the right and does not have the right to be an heir according to Islamic law? 

b. Calculate the distribution of inheritance to each heir according to Islamic law