5 n ( 8 + 8 1 = 2 1 ( 4 40 n + 1 = 4 40 n = 4 − 1 40 n = 3 n = 40 3
5 n + 8 1 = 2 1 5 n = 8 4 − 8 1 5 n = 8 3 ∣ : 5 = 8 3 ⋅ 5 1 = 40 3 A n s w er i s 40 3 .
To solve 8 5 n + 1 = 2 1 , multiply both sides by 8, leading to 5 n + 1 = 4 . After isolating n , we find n = 5 3 .
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