To answer this question, I found a similar problem as shown in the picture below. Let's use the given information: Heat capacity = 3.565 kJ/K, ΔT = 0.26 K. Also, the molar mass of RbBr is 165.372 g/mol.
The solution is as follows:
Molar Heat of Solution = (3.565 kJ/K)(0.26 K)(1/ 5 g)(165.372 g/mol)
Molar Heat of Solution = 30.66 kJ/mol