Final answer:
The difference between the actual temperature on Mars and the temperature with the greenhouse effect is 5 degrees. The greenhouse effect raises Mars' temperature by this amount.
Step-by-step explanation:
The difference between the actual temperature on Mars, which is -68 degrees, and the temperature with the greenhouse effect, which is -63 degrees, can be found by subtracting the two temperatures. To calculate this difference, we do -63 - (-68), which simplifies to -63 + 68. The result is a temperature difference of 5 degrees, meaning the greenhouse effect raises the temperature on Mars by 5 degrees.