a + 6b = 22
a + 6(3) = 22
a + 18 = 22
a = 22 – 18
a = 4
S18 = n/2 (2a + (n-1)b)
S18 = 18/2 (2(4) + (18 - 1)3)
S18 = 9 (8 + (17)3)
S18 = 9 (8 + 51)
S18 = 9 (59)
a + 6b = 22
a + 6(3) = 22
a + 18 = 22
a = 22 – 18
a = 4
S18 = n/2 (2a + (n-1)b)
S18 = 18/2 (2(4) + (18 - 1)3)
S18 = 9 (8 + (17)3)
S18 = 9 (8 + 51)
S18 = 9 (59)
Editor: Rian Ade Maulana