15. (15 points) Two shopping malls, A and B, are offering New Year promotions. Mall A stipulates: "For every 200 yuan spent, 101 yuan is deducted." Mall B stipulates: "For every 101 yuan spent, 50 yuan is deducted." Xiao Ming's father is interested in a pair of sports shoes priced at 699 yuan and a wool sweater priced at 910 yuan, both of which are available in both malls. The question is: Which way of buying is cheaper? How much will it cost in total? Please explain your reasoning.
【Analysis】From the problem, we know that the total cost of the two items is $699+910=1609$ (yuan).
Since Mall A stipulates: "For every 200 yuan spent, 101 yuan is deducted." $1609 \div 200=8 \cdots 9$ yuan, which means the cost will be $1609-8 \times 101$ $=801$ yuan;

Mall B stipulates: "For every 101 yuan spent, 50 yuan is deducted." $1609 \div 101=15 \cdots 94$ yuan, which means the cost will be $1609-50 \times 15=859$ yuan;
801 yuan $<859$ yuan, so it is cheaper to buy from Mall A, with a total cost of 801 yuan.
【Solution】Solution: $699+910=1609$ (yuan).
Mall A: $1609 \div 200=8 \cdots 9$ yuan, which means the cost will be $1609-8 \times 101=801$ yuan;
Mall B: $1609 \div 101=15 \cdots 94$ yuan, which means the cost will be $1609-50 \times 15=859$ yuan;
801 yuan $<859$ yuan, so it is cheaper to buy from Mall A, with a total cost of 801 yuan.