When a number is multiplied by 13, it becomes greater to 105 by an amount with which it is lesser to 105 by now. What is the number

Let the number be x. When multiplied by 13, it becomes 13x. The statement 'becomes greater to 105 by an amount with which it is lesser to 105 by now' means: the excess over 105 after multiplication equals the deficit before multiplication. So 13x - 105 = 105 - x, which gives 14x = 210, so x = 15. Indeed, 15 is 90 less than 105, and 195 (15×13) is 90 more than 105.