ka bantu jawab nomer 5 sama 7 ya

yg difoto itu nomor 5.

No 7
s~ = 12
a = 8 

S~ = a/(1-r) 
1 - r  = a/s~ 
r = 1 - a/s~
r = 1 - 8/12
r = 4/12 = 1/3