Linq - 如何聚合另一个查询的结果

I want to take the results of a where clause on a list and then take that result set and create just one new type that has all its fields constructed from aggregates of the original query. So given the basic example below, is there anyway to combine the 2 linq statements into one? If the original where has no rows then it should return null. Thanks!I want to take the results of a where clause on