Let A ={1, 2, 4, 6, 7, 9, 8} B = {3, 1, 5, 7, 6}. Which set has the maximum cardinality?

Math i have no idea how to do a and b

Without any equipment, you can see stars that are 2{,}800{,}0002,800,0002, comma, 800, comma, 000 light-years away. by looking through a small telescope, you can see stars that are 3{,}112{,}000{,}0003,112,000,0003, comma, 112, comma, 000, comma, 000 light-years away. approximately how many times as far can you see using a small telescope as without any equipment?

If a=0.333333 and b=0.55555, what is the value of a+b