Fernando's calculation of \( 6.4 + (-2.5) = 3.9 \) is part of finding the midpoint of a line segment and is correct for finding the sum of the x-values.
To find the midpoint, the next step involves averaging (dividing by 2) the sum he obtained and then calculating the midpoint using the y-values. Therefore, the correct response is:
Fernando should divide 3.9 by 2, then repeat both steps using the y-values.