Matt had a full jar of marbles. He gave Kayla 3/4 of the marbles. Then Kayla returned 1/3 of a jar's worth of marbles to the jar. How much of the jar is now full of marbles? Enter your answer in simplest fractional form in the box.

A jar of marbles = 4/4 or 12/12
He gave kayla 3/4 or 9/12        he left 1/4 or 3/12 in the jar
Kayla returned 1/3 or 4/12
3/12+ 4/12 = 7/12 
7/12 of the jar is full