I am stuck on these two, please help if you can. thank you :)

What is the area of a pizza with a radius of 40 cm leave the answer in terms of π to find your exact answer 40π cm² 1600π cm² 800π cm² 80π cm² π=pi

Hector and alex traded video games. alex gave hector one fourth of his video games in exchange for 6 video games. then he sold 3 video games and gave 2 video games to his brother. alex ended up with 16 video games. how many video games did alex have when he started?

Asurvey of 2,000 doctors showed that an average of 3 out of 5 doctors use brand x aspirin.how many doctors use brand x aspirin