Step by step
The question
Question: It is −15°C.
It warms up 7 degrees.
What is the temperature now?
1 Write it as a sum
We start at −15.
Warms up means up: add 7.
−15 + 7
Below zero is negative.
−15°C: below zero
warms up 7 → + 7
2 Work it out
Start at −15.
Go up 7.
Careful!
We start at −15, not at 15.
Keep the minus sign.
Careful: not 15 + 7 = 22 ✗
We land on −8°C.
= −8°C
So the answer is −8°C: 8 degrees below zero.
3 Check
Let's check: go back.
−8 minus 7 is −15, where we started.
So the answer is right!
−8 − 7 = −15
Let's look back.
First: write it as a sum.
Then: work it out.
Last: check.
Answer
= −8°C