Exercise 9.6.1 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 9.6.2 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 9.6.3 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 9.6.5 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 9.6.6 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 9.6.7 and 9.6.8 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 9.6.9 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>