Question 753618
I'm not completely sure about what that lady was doing. Here is the interpretation of the problem that makes sense to me, and the solution to the problem as I interpret it.
 
The lady sold half of the oranges she had to the first customer and she kept the other half.
Then she sold half of what she had left to the secomd customer, keeping the rest. She was left with half of half of the original amount, meaning one fourth of the original amount.
Since that was 15 oranges, she must have started with 60 oranges.
In algebra symbols, if she starts with {{{x}}} oranges,
the first customer would leave her with {{{x-(1/2)x= (1-1/2)x=(1/2)x}}}.
Then, the second customer would leave her with
{{{(1/2)x-(1/2)((1/2)x)=15}}} --> {{{(1/2)x-(1/4)x=15}}} --> {{{(1/4)x=15}}} --> {{{x=15*4}}} --> {{{highlight(x=60)}}}