## Answer :

The answer is B: 150

Let a be the age at which the tree reaches maturity

289000 = 900a + 2200(220-a)

289000 = 900a + 484000 - 2200a

289000 - 484000 = -1300a

a = -19500 / -1300

a = 150

A) 188

B) 150

C) 138

D) 148

The answer is B: 150

Let a be the age at which the tree reaches maturity

289000 = 900a + 2200(220-a)

289000 = 900a + 484000 - 2200a

289000 - 484000 = -1300a

a = -19500 / -1300

a = 150