Simplify the following text for a Grade 7 native English-speaking person.
Original: The Fundamental Theorem of Calculus is a theorem that says , where F ( x ) is the antiderivative of f ( x ) .
Simplified: If g is an antiderivative of Æ ' , then g and F have the same derivative , by the first part of the theorem . It follows by the mean value theorem that there is a number c such that , for all x in ( a , b ) .