Find the length of ST​

Will give brainliest series to sigma notation write the following series in sigma notation. 6+10+14+18+22+26+30 example image shown below.

Tickets to a science exposition cost $5.75 each for studentd and $7.00 for adults.how many students and adults went if the ticket charge was $42.75

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?