Let the cost of the shoes be $x.<br><br>&bull; After buying: Sunny has $(350 - x), Fandi has $(410 - x)<br>&bull; 350 - x = 0.7(410 - x)<br>&bull; 350 - x = 287 - 0.7x<br>&bull; 350 - 287 = x - 0.7x &rarr; 63 = 0.3x<br>&bull; x = 63 &divide; 0.3 = $210<br>&bull; Percentage decrease in Sunny's money = \( \frac{210}{350} \times 100\% = 60\% \)<br><br>Final Answer: 60%