We need to determine a number that makes the statement true, we have:
1. x < 7°C, x less than 7, which number would fit? 5°C. In fact, we have plenty of options, but we need to pick just a number. x = 5°C makes the statement true because 5 is less than 7.
2. x < -3°C, x less than -3, we have here a negative number, when we are talking about negative numbers, the values decrease or are lower in that direction, because they are more negative. x = -5°C makes the statement true because -5 is less than -3.