If "÷" denotes "multiplied by", "+" denotes "subtracted from", "–" denotes "added to" and "x" denotes "divided by", then which of the following equation is true?
Triangle ABC is similar to triangle PQR and AB : PQ = 2 : 3. AD is the median to the side BC in triangle ABC and PS is the median to the side QR in triangle PQR. What is the value of ?