Emma, Nora and Zoe each sold an equal number of muffins. Emma collected a total of $42.80 from selling 8 vanilla muffins and some strawberry muffins. Nora collected a total of $46.70 from selling 11 vanilla muffins and some strawberry muffins. How much did Zoe collect if she sold only strawberry muffins?
Nora collected more money than Emma from the sale of the muffins but the number of muffins sold by each girl was the same. This shows that each vanilla muffin is higher priced than each strawberry muffin. 

Amount that Nora collected more than Emma
= 46.70 - 42.80
= $3.90

Number of more vanilla muffins that Nora sold
= 11 - 8
= 3

Extra amount collected from the sale of each vanilla muffin
= 3.90 ÷ 3
= $1.30

Total extra amount collected from the sale of 8 vanilla muffins
= 8 x 1.30
= $10.40

If Emma sold only strawberry muffins, she would collect $10.40 less than her original amount.

Amount that Zoe collected if she sold only strawberry muffins
= 42.80 - 10.40
= $32.40

Answer(s): $32.40