91Ó°ÊÓ

To evaluate any equation involving more than one operation, follow the below order operation

• First assume the case one in which the equation be a=b.
• Secondly assume the case two in which the equation be a=-b.
• Solve the equations of both the cases to find the value of algebraic expression
• After finding the two values of algebraic expression, put the value in the original equation and check the solution

Case1- $a=b$

$\begin{array}{c}−3(2n+5)=−9\\ −6n−15=−9\\ −6n=−9+15\\ −n=\frac{6}{6}\\ n=−1\end{array}$

Case2- $a=−b$

$\begin{array}{c}−3(2n+5)=−(−9)\\ −6n−15=9\\ −6n=15+9\\ n=−\frac{24}{6}\\ =−4\end{array}$

Put the value of n=-1 in the equation $-3\left|2n+5\right|=-9$

$\begin{array}{c}−3|2n+5|=−3|2×−1+5|\\ =−3\left|3\right|\\ =−9\end{array}$

Put the value of n=-4 in the equation $-3\left|2n+5\right|=-9$

$\begin{array}{c}−3|2×−4+5|=−3|−8+5|\\ =−3|−3|\\ =−9\end{array}$

The solution is -1 or -4. Hence, the solution set is $\left(-4,-1\right)$.