Q34:
Of the 2,500 tons of ore mined daily at a quarry, 0.4 percent results in a certain pure metal. In how many days of mining will the total amount of pure metal produced at the quarry be equal to the daily amount of ore mined?
A. 10
B. 100
C. 250
D. 400
E. 1,000
答案是C
請問怎麼算阿??