How many people over the age of 50 do not have HTC One M8 Eye phones?
over the age of 50 refers to age > 50; do not have HTC One M8 Eye phones refers to phone_brand ! = 'HTC' AND device_model ! = 'One M8 Eye';
SELECT COUNT(T1.device_id) FROM gender_age AS T1 INNER JOIN phone_brand_device_model2 AS T2 ON T1.device_id = T2.device_id WHERE T1.age > 50 AND T2.device_model != 'One M8 Eye' AND T2.phone_brand != 'HTC'