OG12-195

laila11

195.a store currently charges the same price for each towel that sells. If the current price of each towel were to increased by 1dollar, 10 fewer of the towels could be bought for 120 dollar, excluding sales tax. What is the current price of each towel?

答案是：4 dollar

看了答案估计“10 fewer of the towels could be bought for 120 dollar”是省了” the unchanged price”.答案解释是设p是现在的价钱，n是可以卖掉小塔得到120dollar的台数.两个方程：（1） pn=120    （2） （p+1）（n-1）=120我的问题是，从这个题目中，怎样可以推导出方程（1）的，题目中好像没有说没变的价钱p与可以卖掉小塔得到120dollar的台数n也是120阿··