In order to reduce the pollution of discarded batteries, the environmental protection mall promises that every 7 old batteries can be exchanged for 1 new battery of the same brand and type. If there is a battery whose unit price is 0.7 yuan per section, and Xiaojuan has 12 yuan, how many batteries of this kind can she use at most?
为了减少废弃电池污染，环保商场承诺每7节旧电池可兑换同品牌同类型新电池1节．如果有一种电池单价是0.7元l节，小娟有12元钱，她最多能用多少节这种电池？
<result>20</result>