What is the sum of fifteen and ten?
1 answer:
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Answer:
= 34.5
Step-by-step explanation:
The n th term of an arithmetic sequence is
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Given = 121.5, then
a₁ + (69 × 1.5) = 121.5
a₁ + 103.5 = 121.5 ( subtract 103.5 from both sides )
a₁ = 18
Hence
= 18 + (11 × 1.5) = 18 + 16.5 = 34.5