There are 3 shapes on a 10x10 grid. Which shape is closest to the gray right_triangle in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: gray right_triangle at (8, 7)
Distance from target shape to green square at (6, 4): 5
Distance from target shape to brown right_triangle at (0, 7): 8
Closest shape is the green square at (6, 4) with distance 5</think>

<answer>(6, 4)</answer>