Let the age of the wise man be x years. And in the question it is said that , 400 reduced by 3 times my age is 133, that is,
400-3x =133
Now we need to solve for x, and for that first we subtract 133 to both sides
400-133-3x=0
267-3x = 0
3x=267
Next is to get rid of 3 by dividing both sides by 3, that is
x = 89 years
And that's his age .
