Answer: 4 months.
Step-by-step explanation:
Given : The amount of money in your savings account after m months is represented by [tex]a = 135m+225.[/tex]
To find : The number of months to have $765 in your savings account.
We put a=765 in the given equation, we get
[tex]765 = 135m+225\\\\\Rightarrow\ 135m=765-225\\\\\Rightarrow\ 135m=540\\\\\Rightarrow\ m=\dfrac{540}{135}=4[/tex]
Hence, you have $765 after 4 months.