Respuesta :
very easy....4 millimeters is the growth every year..as 720 mm is the final one...we can divide it by 4mm to obtain the answer..I.E=180years
(720 millimeters) / (4 millimeters/year) = 180 years
I'm pretty sure that's the only thing you could do with these two numbers
that would give you an answer with units of years .