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Answer:
 6 for $37.50 has the same price
Step-by-step explanation:
The price per wand is found by dividing the price by the number of wands.
 8 for $50  ⇒  $50/8 = $6.25 per wand
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 4 for $20  ⇒  $20/4 = $5.00 per wand  not the same
 6 for $37.50  ⇒  $37.50/6 = $6.25 per wand  is the same price
 10 for $65  ⇒  $65/10 = $6.50 per wand  not the same