How can teachers, according to Islamic law, deal with the decision of the Jordanian Ministry of Education to fail 15% of students, and is it permissible to increase students' grades to avoid wronging some by failing them?

You must record the truth and submit the exam results as they are. The administration is responsible for determining the pass rate and disqualifying students based on their grades. You must not wrong any student by increasing or decreasing their grades. Those with low grades can be disqualified, or a special test can be arranged for them, or differentiation can be made based on other criteria such as good manners and diligence.