What will be the final temperature of the mixture when 20 gm of water at ${30}^{\mathrm{o}}\mathrm{C}$  is mixed with 4 gm of water at  ${80}^{\mathrm{o}}\mathrm{C}$

• A

  $22{.15}^{\mathrm{o}}\mathrm{C}$

• B

  $38{.33}^{\mathrm{o}}\mathrm{C}$

• C

  $18{.42}^{\mathrm{o}}\mathrm{C}$

• D

  $42{.62}^{\mathrm{o}}\mathrm{C}$