书店卖出甲乙两种书共120本,甲种书每本5元,乙种书每本3.75元,卖出的甲种书比乙种书多收入162.5元,甲种书卖出_本.

问题描述:

书店卖出甲乙两种书共120本,甲种书每本5元,乙种书每本3.75元,卖出的甲种书比乙种书多收入162.5元,甲种书卖出______本.

设甲种书有x本,则乙种书有(120-x)本,由题意得:
5x-(120-x)×3.75=162.5,
5x-120×3.75+3.75x=162.5,
             8.75x=162.5+450,
                 x=612.5÷8.75,
                 x=70.
答:甲种书卖出70本.
故答案为:70.