The temperature change in a chemistry experiment was - 2°C every 30 minutes. The initial temperature was 6°C. What was the Temperature after 4 hours?

Initially it was 6°,

30 minutes later it went down to 6 - 2,

30 minutes later it went down to 6 - 2 - 2

let's check the change per intervals of 30 minutes

so after 1 interval of 30 minutes, it went down to 6 - 2

after 2 intervals of 30 minutes, it went down to 6 - 2 - 2, or just 6 - 2 (2)

after 3 interval of 30 minutes, it went down to 6 - 2 - 2 - 2, or just 6 - 2 (3)

after "x" intervals of 30 minutes, it went down to 6 - 2 (x).

now, how many 30 minutes intervals are there in 4hours? well, 8.

so after 4 hours, x = 8, thus it went down 6 - 2 (8) degrees Celsius.