请帮我算道英文算术题,<br/>It cost a collegeRs.0.70 a copy to produce a Programme for the<br/>homecoming footballgame.If Rs.15,000/- was received for advertisements<br/>in the programme,how many copies at Rs.0.50 a copy must be s

请帮我算道英文算术题,
It cost a collegeRs.0.70 a copy to produce a Programme for the
homecoming footballgame.If Rs.15,000/- was received for advertisements
in the programme,how many copies at Rs.0.50 a copy must be sold to make
a profit ofRs.8000/-
刚才找到了答案：广告赚了15000，最后的利润是8000，赔的15000-8000=7000是因为0.7/- 生产而0.5/- 出售，所以出售的数量是（15000-8000）/(0.7-0.5)=35000。这题太不走寻常了，开始怎么我都不肯相信生产成本大于售价。