Exercise 7.6.1 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 7.6.2 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 7.6.3 solved

Signed-off-by: Rodrigo Dias Ferreira <rodrigodias@gmx.de>
Exercise 7.6.4 solved

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