A flat surface of a solid figure

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

Jacks bank statement shows an account balance of -$25.50. which describes the magnitude, of size, of the debt in dollars

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?