The temperature in a city at 6:00 AM was -4°C. During the day, the temperature rose steadily and by 3:00 PM, it reached +9°C. What was the total rise in temperature during that time?

A diver was swimming at a depth of -30 meters below sea level. She then ascended 18 meters towards the surface. What is her new position relative to sea level?

In a classroom test, students were awarded +6 marks for each correct answer and -3 marks for each incorrect answer. No marks were given for unattempted questions. Radhika answered 10 questions correctly and scored a total of 42 marks. How many questions did she answer incorrectly?