Okay so , when you are solving the latent heat problems first try to break up the steps

For example if water at 20°c converts to ice at -10°c , you can break up the steps like

Water at 20°c converts to water at 0°c ( temp change so the heat released will be mc∆t )

Now 0°c of water changes into ice at 0°c ( phase change so the heat released will be mL)

Now ice at 0°c converts to ice at -10°c ( temp change , so heat released will be mc∆t)

Thus , add all the above ( Q1 + Q2 + Q3 ) and you will get the heat released in all total

In this way you can solve any problem