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# Choose the correct answer. If p+3=9, then p is :A) $12$ B) $6$C) $3$D) $15$  Hint: The given problem is related to a linear equation in one variable. To solve this problem, take all the terms containing the variable to the left-hand side of the equation and remaining terms to the right-hand side of the equation. Then solve the equation to find the value of the variable.

Let’s consider the linear equation in one variable given by $ax+b=c$, where $a, b$ and $c$ are constants and $x$ is the variable. On a cartesian plane, this equation represents a straight line parallel to the $y$ axis. To find the value of the variable, we will take all the terms containing the variable to the left-hand side of the equation and remaining terms to the right-hand side of the equation. So, we get:
$ax=c-b$ . Finally, the value of the variable $x$ is given by $x=\dfrac{c-b}{a}$.
For example: Consider the equation $x+9=13$ and compare with $ax+b=c$, we get:
$a=1, b=9$ and $c=13$.
Now, to find the value of the variable $x$, we will take all the terms containing the variable to the left-hand side of the equation and remaining terms to the right-hand side of the equation. So, we get
$x=13-9=4$. Hence, $x=4$ is the solution.
Now, coming to the given question, we are given $p+3=9$. To find the value of the variable $p$, we will take all the terms containing the variable to the left-hand side of the equation and remaining terms to the right-hand side of the equation. So, we get
$p=9-3=6$ . Hence, $p=6$ is the solution.
Hence, option B. is the correct answer.

Note: While shifting the constants from left-hand side of the equation to the right-hand side of the equation, do not forget to change the sign of the constant, i.e. if the sign is positive, change it to negative and vice-versa. Students generally forget to change the sign and end up getting a wrong answer.
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CBSE Class 8 Maths Chapter 2 - Linear Equations in One Variable Formulas  Linear Equations in One Variable  P-Value  Linear Equations One Variable Worksheet  P Wave  The P-Block Elements  The P-Block Elements  P-N Junction  Introduction to p-Block Elements  Preparation of p-Nitroacetanilide  