Work backwards from Box D using the percentages.<br><br>\\(\begin{aligned}<br>\text{Box D} &= 200 \text{ marbles}<br>\\<br>\text{Box C} &= 200 \times 1.25 = 250 \text{ marbles} \quad (25\% \text{ more})<br>\\<br>\text{Box B} &= 250 \times 1.40 = 350 \text{ marbles} \quad (40\% \text{ more})<br>\\<br>\text{Box A} &= 350 \times 0.70 = 245 \text{ marbles} \quad (30\% \text{ fewer})<br>\end{aligned}\\)<br><br>Final Answer: 245