Gwen, Dana and Mary each sold an equal number of scones. Gwen collected a total of $63.80 from selling 7 mango scones and some vanilla scones. Dana collected a total of $69.30 from selling 12 mango scones and some vanilla scones. How much did Mary collect if she sold only vanilla scones?
Dana collected more money than Gwen from the sale of the scones but the number of scones sold by each girl was the same. This shows that each mango muffin is higher priced than each vanilla muffin. 

Amount that Dana collected more than Gwen
= 69.30 - 63.80
= $5.50

Number of more mango scones that Dana sold
= 12 - 7
= 5

Extra amount collected from the sale of each mango muffin
= 5.50 ÷ 5
= $1.10

Total extra amount collected from the sale of 7 mango scones
= 7 x 1.10
= $7.70

If Gwen sold only vanilla scones, she would collect $7.70 less than her original amount.

Amount that Mary collected if she sold only vanilla scones
= 63.80 - 7.70
= $56.10

Answer(s): $56.10