Exercise algebra.equations.linear.balance

Description
Solve a linear equation using only balance rules.

Derivation

6 == 15-9*x

⇒ algebra.equations.linear.balance.con-left-minus, term=15

-9 == -9*x

⇒ algebra.equations.linear.balance.scale-to-one, factor=-9

1 == x

⇒ algebra.equations.linear.flip

x == 1