Answer:
The cost of her dinner without tax or tip is <u>$22</u>.
Step-by-step explanation:
Given:
Anna enjoys having dinner at a restaurant in a town where the sales tax on meals is 10%.
She leaves 15% tip before the sales tax is applied, and the tax is calculated on the pre-tip amount.
She spends a total of $27.50 on her dinner.
Now, to find the cost of her dinner without tax or tip.
Let the cost of dinner without tax or tip be 
So, the tax is:




And, the tip is:




<u><em>As given, she spends a total $27.50 on her dinner.</em></u>
Now, to get the cost of her dinner without tax or tip:



<em>Dividing both sides by 1.25 we get:</em>


Therefore, the cost of her dinner without tax or tip is <u>$22</u>.