A fraction is written in terms of two parts: the number on top is called the numerator and the number on the bottom is called the denominator. We can use the division method to solve this question. To get a decimal, simply divide the numerator 129 by the denominator 21:
129 (numerator) ÷ 21 (denominator) = 6.14
As a result, you get 6.14 as your answer when you convert 4 45/21 (or 129/21) to a decimal.