Question

how do i do this x=b-cd=b, for c

Answer 1

equation doesnt make sense

Answer 2

same way you'd any other equation, the only thing in this case you have 3 sides
left - middle - right

so any operation will include all 3
thus \(\bf x=b-cd=b\\
\textit{subtracting "b" from all 3 sides}\\
x-b=\cancel{b-b}-cd=b-b\implies x-b=-cd=0 \implies x-b=-dc=0\\
\textit{dividing by " -d " to all 3 sides}\\
\cfrac{x-b}{-d}=\cfrac{\cancel{-d}c}{\cancel{-d}}=\cfrac{0}{-d}\implies \cfrac{x-b}{-d}=c=0\)

Answer 3

\(\bf \bf x=b-cd=b\\
\textit{subtracting "b" from all 3 sides}\\
x-b=\cancel{b-b}-cd=b-b\implies x-b=-cd=0\\ \implies x-b=-dc=0\\
\textit{dividing by " -d " to all 3 sides}\\
\cfrac{x-b}{-d}=\cfrac{\cancel{-d}c}{\cancel{-d}}=\cfrac{0}{-d}\implies \cfrac{x-b}{-d}=c=0\)

there... no truncating =)