How to solve math captcha in selenium webdriver using java?.

 public class Mathcaptcha {  
   public static void main(String[] a) throws InterruptedException {  
     // Initialize Web driver    
     WebDriver driver = new FirefoxDriver();  
     //Maximize browser window    
     driver.manage().window().maximize();  
     //Go to Page    
     driver.get("http://localhost/mathquestion/signin");  
     // Type username  
     WebElement username = driver.findElement(By.id("edit-name"));  
     username.clear();  
     username.sendKeys("username");  
     //Type Password  
     WebElement password = driver.findElement(By.id("edit-pass"));  
     password.clear();  
     password.sendKeys("aaaaaa");  
     // get Math question  
 String mathquestionvalue = driver.findElement(By.xpath(".//*[@id='user-login']/div/fieldset/div/div[2]/span")).getText().trim();  
     // remove space if exist  
     String removespace = mathquestionvalue.replaceAll("\\s+", "");  
     // get two numbers   
     String[] parts = removespace.split("\\+");  
     String part1 = parts[0];  
     String part2 = parts[1];  
     String[] parts1 = part2.split("\\=");  
     String part11 = parts1[0];  
     // sum two numbers  
 int summation = Integer.parseInt(part1) + Integer.parseInt(part11);  
     // Math Capcha value  
     WebElement capta = driver.findElement(By.xpath(".//*[@id='edit-captcha-response']"));  
     capta.clear();  
     capta.sendKeys("" + summation);  
     //Click on SignIn button  
     driver.findElement(By.id("edit-submit")).click();  
     //close browser  
     driver.quit();  
   }  
 }