The number of text message her older sister send a day is 14 message.
She sends 12 message per day.
Therefore, for each day she sends 12 message.
Hence,
The message you send per day = 12
Her older sister sends more message than her.
Therefore,
her older sister message = 12 + x
They both send 26 message together a day.
Therefore,
Therefore,
message sent by her sister = 26 - 12 = 14
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