The water price for residents in a certain city is as follows: the part of each household that does not exceed 5 tons per month is charged at 4 yuan per ton, the part that exceeds 5 tons and does not exceed 10 tons is charged at 6 yuan per ton, and the part that exceeds 10 tons is charged at 8 yuan per ton Charged per ton, if a resident of a household pays a total of 108 yuan for water in two months, how many tons is the total water consumption of the resident in these two months?
某城市居民用水价格为：每户每月不超过5吨的部分按照每吨4元收取，超过5吨不超过10吨的部分按每吨6元收取，超过10吨的部分按每吨8元/吨收取，某户居民两个月共交水费108元，则该户居民这两个月用水总量为多少吨？
<result>8.25</result>