B use the app Photomath it helps you with this kinda questions
First you measure the volume then use multiplication
The polynomial is not factorable with rational numbers
There are 2.54 cm in 1 inch. Since we are estimating, we can round the average growth per year to .5 cm which would give you roughly 5 years per inch of diameter (2.5 / .5 = 5). Since we have a tree with a 4 inch diameter, we can estimate the age of the tree is...
4 inches x 5 years/inch = 20 years old.