Exercise algebra.equations.linear.balance

Description
Solve a linear equation using only balance rules.

Derivation

-4 == -x-9

⇒ algebra.equations.linear.balance.con-left-plus, term=9

5 == -x

⇒ algebra.equations.linear.balance.scale-to-one, factor=-1

-5 == x

⇒ algebra.equations.linear.flip

x == -5