I mean this could be both yes and no. An equation is something relating to numbers being either multiplied, divided, subtracted, or added based on the "=" symbol being involved in the equation. This does involve subtraction and most people would think it is an equation. However since the "=" was not included in this, it could also be considered that it isn't an equation.
If there is an "=" in the original equation, than yes. If it isn't, than no.
