Question

help me pls I need to submit this now
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Answer 1

Answer:

tn = a + (n-1)d

80 = 8 + (n-1) 8

80 = 8 - 8 + 8n

80 = 8n

80/8 = n

n = 10

Sn = n/2 × (a + an)

S10 = 10/2 × (8 + 80)

S10 = 5 × 88

S10 = 440

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