Bitmain started shipping in the initial L3+ batches between mid April to End of May, diff went from 90k to 275k, thats actually exactly 3x...sorry you can't do simple maths. In that time they shipped about 10-12k units (this is a conservative estimate since some hash is not all on the LTC network). Being conservative again we can assume they will ship out another 10k in the coming batches between mid july to September. That will be an additional 5-6TH to the network bringing difficulty in the 450-500k range.