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?

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(52803) (Show Source): You can put this solution on YOUR website!
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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   = 45.


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

Solved.

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