There were 13,500 people in the stadium. you multiply the amount of teenagers(270) by 100 then divide by 2, then you get 13,500 people.
1) C is because it’s exactly double the size in both width and length while the others are only gaining one or the other. For example - the a length of the squares is 5 and the length on c is 10, the base on a is 3 long, the base on c is 6. The width on a is 1 and the width on c is 2. You can put these into fractions 5/10 3/6 1/2 but they all equal 1/2. So it’s double the size of a.