Exercise algebra.equations.linear.balance

Description
Solve a linear equation using only balance rules.

Derivation

3 == 4*x+15
algebra.equations.linear.balance.con-left-minus, term=15
-12 == 4*x
algebra.equations.linear.balance.scale-to-one, factor=4
-3 == x
algebra.equations.linear.flip
x == -3