Answer:
The starting temperature was -7 degrees
Step-by-step explanation:
Let's call the inicial temperature by 'X'.
First the temperature doubled, so now it is 2X.
Then, it dropped 10 degrees, so now it is 2X - 10
Then, it increased by 40 degrees, so now it is 2X - 10 + 40 = 2X + 30
Now, the temperature is 16 degrees, so we have that:
2X + 30 = 16
2X = 16 - 30
2X = -14
X = -7
The starting temperature was -7 degrees