I Can't Figure Out the Answer

I have a math question I can not seem to figure out. It is in Spanish.

Si a un terreno rectangular se le aumentase el largo en 15m y el ancho en 6m, la superficie aumentaria en 540m2, y si se disminuye el largo en 6m y el ancho en 5m, le supurficie disminuiria en 215m2. Que dismensiones tiene el terreno?

I also have an English translation

If the rectangular length was increased by 15m and the width by 6m, the surface would increase by 540m2, and if the length is decreased by 6m and the width by 5m, the surface would decrease by 215m2. What is the terrain(surface would make more sense)?

Anyone in algebra that knows how to solve it that would be amazing. Also, none of my other classmates can seem to know it either and I'm the second high scoring in the class.