Let "x" represent the number.
You have to subtract 12 from that number
[tex]x-12[/tex]Then, multiply the difference by -3
[tex]-3(x-12)[/tex]The result must be -54
[tex]-3(x-12)=-54[/tex]From this expression, you can calculate the value of x:
First, distribute the multiplication on the parentheses term, that is, multiply both terms by -3:
[tex]\begin{gathered} (-3)\cdot x-(-3)\cdot12=-54 \\ -3x-(-36)=-54 \\ -3x+36=-54 \end{gathered}[/tex]Second, subtract 36 from both sides of the equal sign:
[tex]\begin{gathered} -3x+36-36=-54-36 \\ -3x=-90 \end{gathered}[/tex]Third, divide both sides by -3
[tex]\begin{gathered} \frac{-3x}{-3}=\frac{-90}{-3} \\ x=30 \end{gathered}[/tex]Peter's number is 30.
