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General arithmetic series rule:
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x = a + d(n-1) .
[a = first term, d = the common difference, n = term]
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So when n = 5, you are looking the the 5th term:
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x = 28 + 7(5-1)
x = 28 + 28
x = 56
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Ans: The 5th term is 56
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