**Answer:**

**7 K.**

**12. 6 °F**

**Explanation:**

**Convert the individual temperatures to Kelvin (Surface temperature and internal temperature) before calculating the temperature difference of the body,**

Let The Surface temperature Be = X °C

And the internal Temperature will be = (X + 7) °C

Converting the surface and the internal temperature to temperature in Kelvin

Surface Temperature of the body (K) = (X + 273) K

Internal Temperature of the body (K) = (X + 7) + 273 = (X + 280) K.

∴ Temperature difference of the body (K) = Internal temperature(K) - surface temperature(K) = (X + 279) - (X + 280)

= X - X + 280 - 273 = 7 K.

∴Temperature difference of the body (K) = 7 K

**Also for Fahrenheit, Convert the individual temperatures (Surface temperature and internal temperature) to Fahrenheit before calculating the temperature difference of the body.**

We use , F = 1.8C + 32

Where C = temperature in Celsius.

also,

Let The Surface temperature Be = X °C

And the internal Temperature of the body will be = (X + 7) °C

Converting to Fahrenheit

Surface Temperature of the body = 1.8X + 32 °F

Internal Temperature of the body = 1.8(X+7) + 32 = 1.8X + 12.6 + 32

Internal Temperature of the body = 1.8X + 44.6 °F

∴ The temperature difference of the body (°F) = Internal temperature(°F) - surface temperature(°F) = (1.8X + 44.6) - (1.8X + 32)

surface temperature(°F) = 1.8X - 1.8X + 44.6 - 32

** surface temperature(°F) = 12. 6 °F.**