Comparing Specific Heat Capacities

Two metal blocks of identical mass, A and B, are heated to the same initial temperature. Each is then placed in a separate calorimeter containing an equal mass of water at the same initial temperature. Block A causes the water temperature to increase by 15.0°C, while Block B causes an increase of 7.5°C. What is the ratio of the specific heat capacity of Block B to that of Block A ($c_B : c_A$)?