aku mohon bantu ya ??

rasio : 2
4+8+16+32 = 60

1. u1 = a = 4
   u 4 = 32
  a.r³ = 32
  4.r³ = 32
     r³ = 32/4
     r³ = 8
     r = 2

S4 =  a(r°n - 1) / r-1
      = 4 (2°4 - 1) /2-1
      = 4(16-1) /1
      = 4*15
      = 60 (A)