As others have already pointed out, the question is ambiguous without more information. Always include the unit; bare magnitudes could mean anything! The studen

As others have already pointed out, the question is ambiguous without more information. Always include the unit; bare magnitudes could mean anything! The student was describing the mediant[1], which was the correct solution when the problem is interpreted with forbiddenvoid'a units[2]. "Adding" fractions with the mediant leads to fun things like the Farey sequence[3] (related to Ford circles[4]) and the very interesting Stern–Brocot tree[5]. (Numberphile has a nice introduction[6] to the fun properties of the Farey sequence) [1] https://en.wikipedia.org/wiki/Mediant_%28mathematics%29 https://en.wikipedia.org/wiki/Mediant_%28mathematics%29 [2] "1/3 (of the students at a table) + 1/3 (of the students at a table) = 2/6 (of the students in the room)" [3] https://en.wikipedia.org/wiki/Farey_sequence https://en.wikipedia.org/wiki/Farey_sequence [4] https://en.wikipedia.org/wiki/Ford_circle https://en.wikipedia.org/wiki/Ford_circle [5] https://en.wikipedia.org/wiki/Stern%E2%80%93Brocot_tree https://en.wikipedia.org/wiki/Stern%E2%80%93Brocot_tree [6] https://www.youtube.com/watch?v=0hlvhQZIOQw https://www.youtube.com/watch?v=0hlvhQZIOQw