Idon't understand how to do this or what the answer is

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?

Of of at a : $6, $8, $7, $6, $5, $7, $5, $7, $6, $28, $30 is?ato .ato .ato .ato .

Is experimental probibilty the same as the observed frequency in math? i need the answer asap!