Please kindly help for this problem

Question

In a mathematics test, there were 20 problems.Each correct answer earned 5 points, and 2 points were deducted for each incorrect answer. No points were added or deducted if a problem was not answered. Amy scored 21 points more than Beatrice, but Beatrice answered more questions correctly than Amy. None of them had a negative total score. What was the smallest possible points Amy had scored?

Answer 1

The minimum Amy had scored is 23.

Amy:

right answer: 5 = 25 points

wrong answer: 1 = 2 points deduction

not answered: 14 questions

total points = 23

Beatrice:

right answer: 6 = 30 points

wrong answer: 14 = 28 points deduction

not answered: 0 questions

total points = 2

So Amy scored 21 points more while Beatrice answered more question.