Jawabanmu

2014-04-04T07:18:09+07:00
P:q = b:a
60 : 45 = 20 : (2r -1)
60 . (2r - 1) = 20 . 45
3 . (2r -1) = 45
6r - 3 = 45
6r = 42
r = 7