91Ó°ÊÓ

Rule: The sum of any like term and its opposite is equal to zero.

Rule: Adding two positive like terms always gives a positive answer; adding two negative like terms always gives a negative answer.

Rule: To find the sum of a positive and a negative like terms, take the absolute value of each like term and then subtract these values.

To add two numbers with the same sign, first add the two numbers and then put their common sign before the answer.

To add two numbers with the opposite sign, and subtract the smaller number from the bigger number. Then put the sign of the bigger number before the answer.

To simplify the expression,$13k−8k−k$ we need to add the like terms. Here 13k and 8k, k are like terms.

Like terms are the terms with same variable.

$\begin{array}{l}13k−8k−k\\ (13k−8k)\text{ â¶Ä‰}−\text{ â¶Ä‰}k\text{ â¶Ä‰â€‰â¶Ä‰}\left(\text{make â¶Ä‰a â¶Ä‰group â¶Ä‰}\right)\\ 5k−k=4k\\ \\ 13k−8k−k=4k\end{array}$

Thus, the value of the expression is.$13k−8k−k=4k$