问两道数学题，请大家帮忙

zephyr_sjz

补充材料：195。Of the science book in a certain suuply room ,50 are on botany,65 are on geology,90are physics ,50 are on zoology ,and 110 are on chemistry.If science books are removed randomly from the supply room,how many must be removed to ensure that 80 of the books removed are on the same science.


A81


B159


C166


D285


E324


198.a merchant paid $300 for a shipment of x identical calculators. The merchant used 2 of the calculators as demonstrations and sold each of the others for $5 more than the average cost of the x calculators. If the total revenue from the sale of the calculators was $120 move than the cost     of the shipment , how many calculators were in the shipment?


A24


B25


C26


D28


E30

Elen

1.


50+65+50+(2*80-1)=324


only 159 books be removed    to ensure that    80 books are on the same science.


2.


(5+300/x) (x-2)-300=120


x=30


    


    

Elen

以下是引用Elen在2004-3-17 6:55:00的发言：
1.



50+65+50+(2*80-1)=324


only 159 books be removed    to ensure that    80 books are on the same science.


2.


(5+300/x) (x-2)-300=120


x=30


    First one correct to no less than 159 books must be removed.