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Mina put $12$ potted plants in a row from one end to the other end of the corridor. They were placed at an equal distance from one another. The distance between the first and the fifth potted plant was $28$ m. Mina went along the corridor from the first pot to the last pot. How many meters did she walk? 
Overseas Competition->Knowledge Point->Word Problem Modules->Interval Problems
$28 \div (5 - 1) = 7$  $7 \times (12 - 1) = 77$ 