Calculate by using addition. Use the additive inverse of the integers in brackets.

The answer is $\boxed{6}$.

The answer is $\boxed{5}$.

The answer is $\boxed{-8}$.

The answer is $\boxed{19}$.

The answer is $\boxed{15}$.

The answer is $\boxed{-19}$.

The answer is $\boxed{-15}$.

The answer is $\boxed{28}$.

The answer is $\boxed{19}$.

j)

The answer is $\boxed{0}$.

k)

The additive inverse of $-1$ is 1, and the additive inverse of $-5$ is 5.

The answer is $\boxed{12}$.

l)

The additive inverse of $-11$ is 11, and the additive inverse of $-8$ is 8.

The answer is $\boxed{38}$.

4. A microwave oven increases the temperature of a piece of meat from $-12^\circ \text{C}$ to $67^\circ \text{C}$. What is the change in temperature?

Initial temperature ($T_{initial}$) $= -12^\circ \text{C}$
Final temperature ($T_{final}$) $= 67^\circ \text{C}$

Subtracting a negative number is equivalent to adding its positive counterpart.

The change in temperature is $\boxed{79^\circ \text{C}}$.

5. Mrs Mojapelo cooks chicken pieces and puts the dish in the freezer. The freezer lowers the temperature from $15^\circ \text{C}$ to $-18^\circ \text{C}$. What is the temperature range?

Highest temperature $= 15^\circ \text{C}$
Lowest temperature $= -18^\circ \text{C}$

The temperature range is $\boxed{33^\circ \text{C}}$.

6. Mr Sobekwa's bank statement shows an amount of $-\text{R}500$. If he previously had $\text{R}325$ in his bank account, how much does he need to put back so that he once again has $\text{R}325$ in his account?

Current balance $= -\text{R}500$
Desired final balance $= \text{R}325$

Subtracting a negative amount is equivalent to adding a positive amount.

Mr Sobekwa needs to put back $\boxed{\text{R}825}$.