Jawabanmu

2014-02-05T21:54:44+07:00
Q = m c Δt
42000 = 0.2 x 4200 x (t-25)
10 = 0.2 x (t-25)
100 = 2 x (t-25)
100 = 2t - 50
150 = 2t
t = 75