Final answer:
Thomas moves one unit east and three units north a total of 12 times from his starting point at (4,3), placing the last pin at coordinates (16,39).
Step-by-step explanation:
Thomas is using a map grid to plan a rail trail. Initially, he places a pin at coordinates (3,0) for the head of the trail. He then moves one unit east and three units north, placing another pin at coordinates (4,3). Following this pattern, he will continue to move one unit east and three units north an additional 12 times, placing a pin each time.
To determine where the last pin will be placed, we need to calculate the final position after the 12 additional moves. Since each move consists of going one unit east and three units north, we can sum these movements to find the total displacement.
12 moves to the east from the second pin's x-coordinate (4) will add 12, resulting in an x-coordinate of 4+12=16. Similarly, 12 moves to the north will add 3*12=36 to the second pin's y-coordinate (3), giving us a y-coordinate of 3+36=39. Therefore, the final coordinates after 12 more moves will be (16,39).