Destroy 2 Air Defense at once

On https://www.reddit.com/r/ClashOfClans/comments/3rjgzi/strategy_destroy_two_air_defenses_at_once_with/ a simple way is detailed to destroy 2 (level 6) air defense:

For this, you must drop between both air defende::

• 2 lightnings (level 5)
• 1 earth quacks
• next a last lightning

Here table with lightning level and earthquake level to use to destroy Air Defense depending of his level:
Notice:

• first column: lightning level - first line = air defense level
• Green numbers show that it is the most efficient strategy for that level of lightning and Red numbers mean you can destroy the AD with the combo, though there is a more efficient strategy.
  So if you are going to hit a level 5 AD with your level 6 lightning, you search for the cell corresponding to those levels in the tables. The first one is "lightning + no EQ", and it shows 2. So you need 2 lightnings. In the other tables (lightning + lvl x EQ), it shows 2, but in red meaning you don't need the EQ.
  Again, if you are going to hit a level 7 AD with a level 1 lightning and level 1 EQ, it shows 4 in red meaning there is a more efficient way. That is without the EQ, or 3 lightnings and a level 3 EQ.

To resume 

• Red = No point using Earthquake
• Green = Earthquake has effect

Source: https://www.reddit.com/r/ClashOfClans/comments/42wi30/strategy_updated_fixed_be_all_and_end_all