停车场只有黑白两种车，白车与黑车的比率是$$3:8$$，黑白车的总数是$$242$$辆．请问黑车比白车多多少辆？  ratio比率； a total of 总数； more．．than 比．．多．  白车数量：$$\frac{3}{11}\times 242=66$$辆，黑车数量：$$\frac{8}{11}\times 242=176$$辆．黑车比白车多$$176-66=110$$辆． 
（这是一道挑战题！）There are only white cars and black cars．$$If$$ the ratio of white cars to black cars is $$3$$ to $$8$$ and there are a total of $$242$$ cars， how many black cars and white cars are there？ 
- $$66$$ 
- $$110$$ 
- $$129$$ 
- $$176$$ 