Science does not know the 'true age' of the earth with 100% confidence. Since true science deals with what is observable, there is no observational data. Whatever answer you believe will be taken on faith.
If you assume that all the geologic processes which are occurring now (rain, sediment deposits, etc.) have always occurred at the same rate, you will have one answer. This is called 'uniformitarianism'. If you believe that there have been major changes in those processes, the answer will be different. Scientists in previous generations believed that geological cataclysms changed the earth and those processes. This is termed "cataclysmic geology'.
If you subscribe to Biblical accounts, the earth is about 6000 years old.
If you believe that radiometric dating is accurate, then you arrive at an answer of millions if not billions of years, depending on which method and calculations you use. Like many algebraic type equations, there are several unknowns and assumptions in the formulas. Some of the scientists are less than honest and do not tell the public about all the unknown variables. Remember how frustrating algebra problems were to solve when you had just two unknown variables? Although radiometric dating sound impressive with all the numbers, it requires faith in their ability to crunch numbers based on assumptions. No one has seen uranium emit radioactivity for all those thousands of years. Consider how the cities of Hiroshima and Nagasaki have been rebuilt when the scientific experts claimed that the area would be radioactive for hundreds of years.
So, it is a matter of which system you put your faith in as to how old you consider the earth to be.