Solution:
Given d = 7,22nd term = 149 , ⇒ a+21d = 149⇒a+21(7) = 149⇒a+147 = 149⇒a=149-147=2Sn = (n/2)(2a+(n-1)d)S₂₂ = (22/2)(2×2+(22-1)7)S₂₂ = 11(4+21(7))S₂₂ = 11(4+147)S₂₂ = 11(151)S₂₂ = 1661.
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