tolong yaaa pake cara

U5 = 23 -----> a + 4b = 23
U7 = 33 ------> a + 6b = 33

a + 4b = 23
a + 6b = 33
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-2b = -10
b = -10/-2
b = 5

b = 5 disubtitusikan ke a + 4b = 23
a + 4b = 23
a + 4 . 5 = 23
a + 20 = 23
a = 23 - 20
a = 3

Un = a + (n - 1)b
U20 = 3 + (20 - 1) 5
U20 = 3 + 19 . 5
U20 = 3 + 95
U20 = 98

Moga membantu...