How old am I if 400 reduced by 3 times my age is 124? Let my age be a. We're given an algebraic expression: 3 times my age means we multiply a by 3: 3a 400 reduced by 3 times my age means we subtract 3a from 400: 400 - 3a The word is mean an equation, so we set 400 - 3a equal to 124 400 - 3a = 124 To solve for a, we type this equation into our search engine and we get: a = 92