The given equation is
[tex]\lvert{3x+7}\rvert=4x[/tex]We will solve it in this way
[tex]3x+7=4x,3x+7=-4x[/tex]For the 1st equation
[tex]3x+7=4x[/tex]Subtract 7 from each side
[tex]\begin{gathered} 3x+7-7=4x-7 \\ 3x=4x-7 \end{gathered}[/tex]Subtract 4x from both sides
[tex]\begin{gathered} 3x-4x=4x-4x-7 \\ -x=-7 \\ x=7 \end{gathered}[/tex]For the 2nd equation
[tex]3x+7=-4x[/tex]Subtract 3x from both sides
[tex]\begin{gathered} 3x-3x+7=-4x-3x \\ 7=-7x \end{gathered}[/tex]Divide both sides by -7
[tex]\begin{gathered} \frac{7}{-7}=\frac{-7x}{-7} \\ -1=x \end{gathered}[/tex]The solutions are
7, -1
The answer should be B
