Question

The temperature on Monday was -1.5 Celsius the temperature on Tuesday was 2.6 Celsius less than the temperature on Monday what is the temperature on Tuesday

Answer 1

less than means we will subtract 2.6 from the temperature on monday to get the temperature on tuesday.
on monday the temperature was -1.5
on tuesday the temperature was:
-1.5-2.6 = -4.1 degrees celcius