Answer: The tree grow by 23.4 inches.
Step-by-step explanation: Given that an oak tree grows at a rate of
inches per month.
We are to find the length by which the tree grow in
months.
We will be using the UNITARY method to solve the given problem.
In one month, the length of the tree grew is
![(18)/(5)~\textup{inch}.](https://img.qammunity.org/2019/formulas/mathematics/middle-school/abc5oas2anhks9ofov44r63golhcs7to9d.png)
Therefore, in
months, the length of the tree grew is given by
![(18)/(5)*(13)/(2)=(117)/(5)=23.4~\textup{inches}.](https://img.qammunity.org/2019/formulas/mathematics/middle-school/w7u5wdq14uxw06emhkgmrmmlns012d6lmq.png)
Thus, the tree grow by 23.4 inches.