An old man said that if you add 17 to his age, divide it by 4, subtract 15 and multiply it by 10, you will be 100 years old. How old is the old man

An old man said that if you add 17 to his age, divide it by 4, subtract 15 and multiply it by 10, you will be 100 years old. How old is the old man

Let the age of the elderly be x, the formula is ((x + 17) △ 4-15) X10 = 100, and the formula is 83 years old