Answer:
-10.1°C
Step-by-step explanation:
You want this morning's temperature if it is 5.9°C lower than yesterday's temperature of -4.2°C.
The new temperature is found by adding the change to the old temperature. A drop in temperature is a negative change.
-4.2°C +(-5.9°C) = (-4.2 -5.9)°C = -10.1°C
The temperature this morning was -10.1 °C.