The liquids at temperature $60^{\circ}C$ and $30^{\circ}C$ respectively have masses in the ratio $3:4$ and their specific heats in the ratio $4:5$. If the two liquids are mixed, the resultant temperature is :

Question

( A ) $41.25^{\circ}C$
( B ) $40^{\circ}C$
( C ) $70^{\circ}C$
( D ) $50^{\circ}C$