Matemáticas con C Sharp

public int number_1 = 13
public int number_2 = 25

public int total_number = number_2 - = number_1
Console.Writeline(total_number) //result should be 12 :)

public int total_number_2 = number_1 + = number_2
Console.Writeline(total_number_2) //result should be 28 :)

public int total_numner = number_2 + = number_2
Console.Writeline(total_number_2) //result should be dubble the amount of number 2: 50 :)
dl.idiot..