A fraction is usually split into two parts: the first part is the number on top, called the numerator; and the second part is the number on the bottom, called the denominator. These are both separated by a line called the “divisor line”. We can use the division method help to solve this question: to get a decimal, simply divide the numerator 43429 by the denominator 140 (which you can enter in any calculator):
43429 (numerator) ÷ 140 (denominator) = 310.21
And finally, you get 310.21 as your answer when you convert 308 309/140 (or 43429/140) to a decimal.