$a$ and $b$ are real numbers and satisfy $ab^2=\frac{27}{5}$ and $a^2b=135$. Compute $a+5b$.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
$a$ and $b$ are real numbers and satisfy $ab^2=\frac{27}{5}$ and $a^2b=135$. Compute $a+5b$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
18
$a$ and $b$ are real numbers and satisfy $ab^2=\frac{27}{5}$ and $a^2b=135$. Compute $a+5b$.
train