An old man said, "add 17 to my age and multiply it by 1 / 4, then subtract 15 and divide it by 1 / 10. It's exactly 100 years old." how old is this old man this year? (note! We must use formula, not equation ~)

An old man said, "add 17 to my age and multiply it by 1 / 4, then subtract 15 and divide it by 1 / 10. It's exactly 100 years old." how old is this old man this year? (note! We must use formula, not equation ~)

"Add 17 to my age and multiply by 1 / 4, subtract 15 and divide by 1 / 10, it's exactly 100 years old." the age of "add 17 to my age and multiply by 1 / 4, subtract 15" is 100x1 / 10 = 10 years old. The age of "add 17 to my age and multiply by 1 / 4" is 10 + 15 = 25 years old. The age of "add 17 to my age" is 2