Start at (-3,9). The increase in x from this point to the midpoint (3,3) is 6. Add 6 to the x-coordinate of (3,3), obtaining 9, which is the x-coordinate of the other endpoint of the line segment.
Next, notice that y decreases by 6 from 9 to 3 as we travel from (-3,9) to (3,3). Decrease y again by 6: 3 less 6 is -3. So the y-coordinate of the other endpoint is -3.
Thus, the coordinates of the other endpoint are (9, -3).
Let's check whether this is correct or not. According to the midpoint formula, e find the x-coordinate of the midpoint by summing up the endpoint x values and dividing this sum by 2: (-3+9)/2 = 3. This agrees with the given midpoint (3,3).
