Can someone help me with these questions. (It’s a quiz btw)

Could someone with number 1 and 2

Acylinder with a base diameter of x units has a volume of jxcubic units which statements about the cylinder are true? check all that apply. the radius of the cylinder is 2 x units. the radius of the cylinder is 2x units. the area of the cylinder's base is 200 square units. the area of the cylinder's base is a square units. the height of the cylinder is 2x units. the height of the cylinder is 4x units. mark this and return save and exit next submit

Suppose that sahil knows that 45 people with ages of 18 to 29 voted. without using a calculator, he quickly says then 135 people with ages of 30to 49 voted. is he correct? how might sohil have come up with his answer so quickly?