The desired number is the difference between the number of messages sent by the 16th day and the number sent by the 9th day:
... n = t(16) - t(9)
... n = (40×√16) - (40×√9)
... n = 40×(4 - 3) = 40
40 text messages were sent between the ninth and sixteenth day of the month.
You have 9n and -7 in total so the answer is 9n-7. You add up all the numbers and then add up the numbers with n attached to them
Answer:
t>−74
Step-by-step explanation:
I hope this help helps
