Jawabanmu

2014-03-10T20:44:27+07:00
Q=mcΔT
84000=0,5.4200.ΔT
ΔT= \frac{84000}{2100}
ΔT=40

Takhir = ΔT + Tawal
Takhir= 40+20
Takhir = 60
2014-03-10T20:45:40+07:00
84000 = 4200 x 0,5 x Δt
84000 = 2100 x Δt
40      =Δt
40-20 =Δt
20      =Δt