SOLUTION: Two APs Have The Same First And Last Terms. The First AP Has 21 Terms With A Common Difference Of 9. How Many Terms Has The Other AP If Its Common Difference Is 4?

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Question 1148235: Two APs Have The Same First And Last Terms. The First AP Has 21 Terms With A Common Difference Of 9. How Many Terms Has The Other AP If Its Common Difference Is 4?
Answer by ikleyn(52802) About Me  (Show Source):
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(1)  The difference between the last and the first term of the first AP is 20*9 = 180.


(2)  The difference between the last and the first terms of the second AP is the same, 180.


(3)  The numbers of gaps between the terms of the second AP is  180%2F4 = 45.


(4)  Hence, the number of terms in the second AP is  45+1 = 46.    ANSWER

Solved.