How much does Samsung mobile phone need to pay the developer for Android?

Android is free, but all hardware manufacturers who pre-install Android have to pay patent fees to Google, Microsoft and Apple.

For example, every time Samsung produces an Android phone, it needs to pay Microsoft a patent fee of 10 ~ 20 dollars, Google a patent fee of 10 dollars and Apple a patent fee of 10 dollars. Similarly, HTC also needs to pay patent fees.

The system is free, but the patent fee cannot be exempted.