Suatu barisan aritmetika U1+U3+U5=30 dan U2+U4+U6=39. Suku ke-51 barisan tersebut adalah...... A.150 B.154 C.157 D.159

u1 + u3 + u5 = 30
a + a + 2b + a + 4b = 30
3a + 6a = 30 |÷3| ==> a + 2b = 10
u2 + u4 + u6 = 39
a + b + a + 3b + a + 5b = 39
3a + 9b = 39 |÷3| ==> a + 3b = 13
eliminasi
a + 2b = 10
a + 3b = 13
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-b = -3
b = 3
a + 2(3) = 10
a + 6 = 10
a = 4
U51 = a + 50b
U51 = 4 + 50(3)
= 154