8 、Xiaoming's father needs to ride a mountain bike for 10 minutes every day to go to work, and then take the subway for 40 minutes. One day, the subway broke down, so he rode his bike all the way to work, which took a total of 3 and a half hours. Then, how many times faster is the subway compared to the mountain bike?
【Answer】 5
Analysis: Let the cycling speed be $\mathrm{V}_{1}$, and the subway speed be $\mathrm{V}_{2}, 10 \mathrm{~V}_{1}+40 \mathrm{~V}_{2}=210 \mathrm{~V}_{1} \quad \mathrm{~V}_{2}=5 \mathrm{~V}_{1}$, which means 5 times