Find a number whose double is 45 greater than its half.

Four-fifth of a number is more than three-fourth of the number by 4. Find the number.

The difference between the squares of two consecutive numbers is 31. Find the numbers.

Find a number such that when 5 is subtracted from 5 times that number, the result is 4 more than twice the number.

A number whose fifth part increased by 5 is equal to its fourth part diminished by 5. Find the number.