jika diketahui deret aritmatika  2+4+6+....+3p=930 maka nilai p+5 :

a = 2
b = 4 - 2 = 2
Sn = 930
Sn = n/2(2a + (n - 1)b)
930 = n/2(2(2) + (n - 1)2)
930 = n/2 (4 + 2n - 2)
930 = n/2 (2n + 2)
930 = n² + n
n² + n - 930 = 0
(n - 30)(n + 31) = 0
n = 30 atau n = -31
pakai yg positif n = 30
U30 = 3p
Un = a + (n - 1)b
3p = 2 + (30-1)2
3p = 2 + 58
3p = 60
p = 20
maka
p + 5 = 20 + 5 = 25