Question

No:9 gimana caranya ya??

Answer 1

U₁ = 20
U₂ = 24
U₃ = 28 

a = 20
b = 24-20 = 4

Un = a + ( n - 1 ) b
U₃₅ = 20 + ( 35 - 1 ) 4
      = 20 + (34) 4
      = 20 + 136
      = 156

Banyak kursi pada baris ke-35 = 156 kursi