Exercise algebra.equations.linear.balance

Description
Solve a linear equation using only balance rules.

Derivation

0 == 2*x+9

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

-9 == 2*x

⇒ algebra.equations.linear.balance.scale-to-one, factor=2

-9/2 == x

⇒ algebra.equations.linear.flip

x == -9/2