= Solution
Number the fused <heterocycle> as a 2,3-dihydrobenzofuran: <oxygen> is position 1 and the acetamido <substituent> occupies aromatic position 6. \b[Position 5 is the preferred site of <electrophilic substitution>.] It is para to the ring <oxygen> and ortho to the acetamido group, so both groups stabilize its <Wheland intermediate> by <resonance donation>. Position 7 also receives donation, but lies between the two <substituents> and is more crowded. Position 4 lacks the same combination of directing effects.
The aryl <oxygen> donates a <lone pair> into the aromatic system. The acetamido <nitrogen> can also donate into the ring, although its <lone pair> is shared with its own <carbonyl group>, so it is less activating than a free amino group. Comparing resonance-stabilized intermediates and steric accessibility gives the position-5 prediction; simply counting heteroatoms does not.
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