please using java Answer questions

1- Write a program that reads the circle radius form the user, and prints the circle area 2- Write a program that reads three values from the user, and outputs the minimum number 3- Write a program that calculates the tax a citizen should pay according to his salary, If he gets less than 500, he doesn't pay tax If he gets 500 - 799, he pays 3% tax If he gets 800-1200, he pays 5% if he gets more than 1200, he pays 7%