If the first number is 20% less than the third number and the ratio of the second to the third number is 7 : 10, then the average of the first and the third number is how much percent more than the second number?

In a certain college, 50% of the students are below 18 years of age. The number of students above 18 years of age is 23 of the number of students who are exactly 18 years of age. If the number of students who are exactly 18 years of age is 60, what is the total number of students in the college?

When 60% of a number is added to another number, the second number increases to 140% of its value. What is the ratio between the first and the second number?