When Ron-Jon multiplies the second equation by
he must multiply both sides for the equality to hold. In his solution Ron-Jon only multiplied the left-hand side but forgot the right-hand side.
When the second equation is multiplied by
it should instead look like this
Ron-Jon's system then looks like this.
Adding the equations will lead to the
-terms eliminating each other.
The correct value of
is then found by solving the resulting equation.