Answer:
The temperature at the base camp Friday evening is - 6 degrees Celsius.
Explanation:
To get the temperature at a mountain base camp on Friday evening, we must translate statement into a mathematical form:
(i) The temperature at a moutain base camp was - 2 degress Celsius on Thursday:

(ii) Friday morning, the temperature was 1 degree Celsius lower than it was on Thursday:

(iii) Friday evening, the temperature was 3 degrees Celsius lower that it was that morning:

The temperature at the base camp Friday evening is:



The temperature at the base camp Friday evening is - 6 degrees Celsius.