Step-by-step explanation:
q = mCΔT
where m is mass,
C is specific heat capacity,
and ΔT is change in temperature.
Make sure all your units match. Assuming the substance is water, C = 4186 J/kg/°C.
Trial 1:
q = (0.4 kg) (4186 J/kg/°C) (78°C)
q = 130,600 J
Trial 2:
q = (0.6 kg) (4186 J/kg/°C) (78°C)
q = 195,900 J
Trial 3:
q = (0.45 kg) (4186 J/kg/°C) (75°C)
q = 141,300 J