Answer:
(L + 10)/(L + 16) = 0.8
Explanation:
She needs to answer L more questions to get a grade of 80%.
When she answers L more questions correctly, she will have answered L + 10 questions correctly.
The total number of questions will be L + 16.
L + 10 must be 80% of L + 16
(L + 10)/(L + 16) = 0.8