Question 926131
The way to start is to assign a variable to cost or price for  apples Celia bought.  Work through a transcription of symbolism from all of that.


v, cost of the 12 apples
v/12, PRICE paid per apple;
She sold 10 apples at {{{v/12+0.20}}}  dollars per apple.


She paid v dollars.
She took revenue of {{{10(v/12+0.2)}}}.
Her profit was 1 dollar.


{{{highlight(10(v/12+0.20)-v=1)}}}.
That means, the difference between revenue and cost is profit.  Solving first for v will allow you to compute the price at which she sold her remaining 10 apples.