Step by step
The question
Question: The temperature is 5°C.
It drops 12 degrees.
What is the temperature now?
1 Write it as a sum
We start at 5.
Drops means down: take away 12.
5 − 12
Below zero is negative.
5°C
drops 12 → − 12
2 Work it out
Start at 5.
Go down 12.
We pass 0.
Careful!
We start at 5, not at 5.
Keep the minus sign.
Careful: not 5 − 12 = -7 ✗
We land on −7°C.
= −7°C
So the answer is −7°C: 7 degrees below zero.
3 Check
Let's check: go back.
−7 plus 12 is 5, where we started.
So the answer is right!
−7 + 12 = 5
Let's look back.
First: write it as a sum.
Then: work it out.
Last: check.
Answer
= −7°C