One more thing: if I type a b/c d in a text editor and paste it into Wolfram|Alpha with the MathInput button active, it is interpreted as a(b/c)d, because the two-dimensional input does not get triggered by the pasting.
a b/c d
a(b/c)d
I believe it is common for ratio operator precedence to group everything to the right apart from everything to the left, unless and until a subsequent ratio sign (colon) is encountered.
