Solution 
First simplify the fraction on the left: 12/20 = 3/5
Cross Multiplication: First fraction numerator 
× second fraction denominator = first fraction denominator ×
second fraction numerator. 3 × 10 = 5n. Dividing both sides by 5,  n = 3 × 10 ÷ 5 = 6
  Alternate Explanation:  First simplify the fraction on the left: 12/20 = 3/5
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