Physics Please someone help please
posted by Akbar on .
A 34 g glass thermometer reads 21.6°C before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 38.7°C. What was the original temperature of the water?
.135(4186)(Tf38.7)=.034(840)(Tf21.6)
=565.11Tf+21869.752=28.56Tf616.896
solve for Tf
Tf= 37.88 degree celcius but its wrong please help!
thank you

m1•c1•(38.721.6) = m2•c2•(t38.7)
m2 =ρ•V =1000• 135•10^3•10^3 =0.135 kg,
c1 =840 J/kg , c2 = 4180 J/kg.
t 38.7 = 0.034•840•17.1/0.135•4180 = 0.865 oC.
t = 38.7+ 0.865 =39.57oC 
A 30 g glass thermometer reads 21.6°C before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 38.1°C. What was the original temperature of the water?
Please provide step by step equation and answer