Respuesta :
The second equation is correct. Nina initally had 17 marbles in her bag. Her mother placed m marbles into her bag. After counting, she now has 34 marbles. Part of this 34 marbles is already her initial 17 marbles. Therefore, 17 marbles initially + m unknown marbles = 34 marbles. The equation 17 + m = 34 is the answer.