Question

How do you solve $11x - 21 = 8x + 15?$

Answer 1

Hint: Move all the terms on one side of the equation, when you any term from one side to another then the sign of the terms also changes. Then will make the pair of like terms and then simplify it for the required unknown value for “x”.

Complete step by step solution:
Take the given expression: $11x - 21 = 8x + 15$
Move the term with the variable from the right hand side of the equation on the left hand side of the equation. When you move any term from one side of the equation to another then the sign of the term also changes. Positive terms become negative and vice versa. Also move constant on the right hand side of the equation.
$ \Rightarrow 11x - 8x = 15 + 21$
Simplify the above equation finding the difference for the terms on the left hand side of the equation.
$ \Rightarrow 3x = 36$
The term multiplicative on one side if moved to the opposite side then it goes to the denominator.
$ \Rightarrow x = \dfrac{{36}}{3}$
Find the factors for the term on the numerator on the right hand side of the equation.
$ \Rightarrow x = \dfrac{{12 \times 3}}{3}$
Common factors from the numerator and the denominator cancel each other. Therefore remove from the numerator and the denominator in the above expression.
$ \Rightarrow x = 12$
This is the required solution.

Note: Be careful about the sign convention and framing the given expression in the simplified form. When you move any term from one side of the equation to another side then the sign of the term also changes. The positive term becomes the negative term whereas the negative term becomes the positive term.