Problems on Numbers - General Questions

When 4 times a number is increased by 10, the result is 126. What is the number?

The sum of three consecutive integers is 21. What is the largest of them?

The sum of three consecutive integers is 87. What is the largest of them?

The difference between a two-digit number and the number obtained by interchanging its digits is 9. What is the difference between the two digits?

When 4 times a number is increased by 19, the result is 103. What is the number?