In an exam 3 marks are awarded for each correct answer, and one mark is deducted for each incorrect answer. If Dia attempts 35 questions and scores 69 marks, find the number of correct answers.

Following chart shows experience (in years) for employees working in an organization. Employees with experience of 4 years and above are considered senior staff, while rest are considered junior staff. Find the number of senior staff in the organization.

Students from grade 8 class decided to collect money for earthquake relief. The amount (in SR) collected by each students equals to number of students in the class, If they collected a total of SR8836, how many students were there in the class?

A shopkeeper sells two qualities of coffee at the rates of SR44 per kg. and SR42 per kg, gaining 10% and 20% profit respectively. If he mixes the two variants in the ratio 2:3 and sells the mixture at SR40.7 per kg., what is his gain or loss?

Dia picks a three digit number and subtract it from the same number after reversing order of its digits. This difference will always be fully divisible by which of following number?