The height of the mountain is 5 km, and the temperature at the foot is + 25. What is the temperature at the top of the mountain?

For a clearer and more convenient solution, it is advisable to use a special algorithm.

First, read the problem carefully (at least 2 times) and note what you want to find.
Then find in the problem statement how many degrees the temperature changes with each kilometer, if this is not indicated in the problem, then take a number that is suitable for almost all mountains – 6 degrees.
Then multiply the number of changes in temperature with each kilometer by the height of the summit.
Subtract from the degrees at the foot of the mountain, the resulting number in the third paragraph.
Record your answer.
The solution of the problem
After I have studied the theory, you can start solving the problem and I will do it using the algorithm that I gave above.

After reading the problem statement, I see that I need to find the temperature at the top of the mountain.
The problem statement does not say how much the temperature changes with each kilometer, so I take the average number 6.
I multiply the number of temperature changes by the height of the summit. 6 * 5 = 30
Subtract from the temperature of the base of the product of numbers in point 3. 25-30 = -5
Answer: -5 degrees.