If 12 balls fit in 2 boxes, 6 balls fit in 1 box. 78 / 6 = 13. 78 balls fit in 13 boxes. x = 13.
We set up the proportion 2 12 = x 78 to solve for x . By cross-multiplying, we find that x = 13 . This means that 78 balls will fit into 13 boxes.
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