Subtracting 8 from both sides of the equation will isolate the variable n, allowing Jonny to solve for the value of n.
The reason why Jonny is subtracting 8 from both sides of the equation is to isolate the term containing the variable n on one side. By subtracting 8 from both sides, he is simplifying the equation and moving the constant term (8) to the other side of the equation. This will help in further solving the equation and finding the value of n.