题目

China has input several billion yuan of money to stop the dirty water waste on the upper and middle area of the Pearl River from polluting the lower reaches of the river, especially the Macao Spe­cial Administrative Region. The Guangxi Zhuang Autonomous Region in the upper and middle reaches of the Pearl River has been rapidly urbanized (城市化) and industrialized in recent years, leading to a rise in the amount of urban rubbish to the damage of the land, rivers and atmosphere. Refuse dumps and special plants in most cities treat rubbish to make it harmless, with 5,800 tons of wastes being与是同类项，则a+b的值是________.