[求助}明天就考了,再问下四月jj57题到底应该选哪个

shalling

57. J brought pens in boxes of 5 for $0.8 each box, she sold all pens in boxes of 3 for $0.6 each box. If she made a profit of $8, how many boxes did she brought and sold?

A. 40;  B 80;  C 100;  D 200;  E  400

scujean

【我的 想法】(题目的数字可能有错,我的是观念！)
1.how many boxes did she brought and sold?←这句的意思要算[买的+卖的]盒数
2.我做题时：0.8/5=买的每支笔的成本, 0.6/3=卖的每支笔的售价, 令卖了x支笔
[0.6/3-0.8/5]*x=8→x=200支笔→那么等于卖了200/3=约66盒,我假设卖的支数=买的支数，所以 买的盒数200/5=40→所以[买的+卖的]盒数=66+40

   还是要视考场的题目而定..

小心buy to sold 的问法