Exercise algebra.equations.linear.balance

Description
Solve a linear equation using only balance rules.

Derivation

0 == 4*x+18
algebra.equations.linear.balance.con-left-minus, term=18
-18 == 4*x
algebra.equations.linear.balance.scale-to-one, factor=4
-9/2 == x
algebra.equations.linear.flip
x == -9/2