I need to find the specific heat of copper sing this formula

I need to find the specific heat of copper sing this formula – mass(specific heat)(change in temperature) + (mass)(specific heat)(change in temperature)=0 the mass of water is .1kg sh is 4180 j/kg temperature change – 2  for copper the numbers are mass .018 kg sh- need to find temp change- 76      for my answer i get .611 but it needs to be around .386 and i don’t know what i’m doing wrong! please help!