I planted a 3 ft tree that has grown the same amount each year.at the end of the third year , the tree was 1/5 taller than it was at the end of the second year .the tree is now 18 feet tall. How many years ago did I plant the tree?
15 years ago
at the end of year 2, height
at the end of year 3, height
but we are also told that
combining eqns (2) and (3) (both equal to
Total growth since planting
At 1 ft/year this has taken 15 years