Answer:
25
Step-by-step explanation:
We require to solve for n, hence
n(n + 1) = 325
multiply both sides by 2 to eliminate the fraction
n(n + 1) = 650
n² + n = 650
subtract 650 from both sides to have equation in standard form
n² + n - 650 = 0 ← in standard form
(n + 26)(n - 25) = 0 ← in factored form
equate each factor to zero and solve for n
n + 26 = 0 ⇒ n = - 26
n - 25 = 0 ⇒ n = 25
however, n > 0 ⇒ n = 25