7.3. On an island, there live 100 people, some of whom always lie, while the rest always tell the truth. Each resident of the island worships one of three gods: the Sun God, the Moon God, and the Earth God. Each resident was asked three questions:
(1) Do you worship the Sun God?
(2) Do you worship the Moon God?
(3) Do you worship the Earth God?
To the first question, 60 people answered: “Yes”; to the second question, 40 people answered: “Yes”; to the third question, 30 people answered: “Yes”. How many of them were lying?
7.3. People who always tell the truth are called "honest people", and those who always lie are called "liars". Each honest person will only answer "yes" to one question, while each liar will answer "yes" to two questions. Let the number of honest people be $x$, and the number of liars be $y$. Therefore, $x+2y=130$. Since there are 100 people living on the island, we have $x+y=100$. Thus, it is known that $y=30$ people are telling lies.