The corresponding extension method syntax is:

  var filteredCustomers = customers
      .Join(orders,
          c => c.customerid,
          o => o.customerid,
          (c, o) => new { Customer = c, Order = o }
      )
      .Where(x => x.Customer.IsMale && x.Customer.Age > 30)
      .Where(x => x.Order.IsPending);