Which of the following is a proportion?

The size of a certain cell is 2.5*10^-9m. another cell is 1.5*10^3 times larger. how large is the larger cell in scientific notation?

Aprojectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t2 + 704t. after how many seconds does the projectile take to reach its maximum height?

How do the definitions, properties, and postulates you've learned about line segments, parallel lines, and angles to define the shapes of polygons