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Mp model with mathematics explain how the number of text messages dario sent and the cost form an arithmetic sequence. then write an expression to find dario's text messaging bill if he sends n text messages over 250.

5500 dollars is placed in an account with an annual interest rate of 6.5%. to the nearest tenth of a year, how long will it take for the account value to reach 19700 dollars?

Ican figure out 20 shares multiply by $117.98 =2359.6920 shares multiply by $124.32=2486.40then take 40 shares multiply by $128.48=5139.20after that i'm lost any be greatly appreciated.