Because you're given how much Jackson already has, we're going to start off with subtracting that number from the total of the new car to find how much he needs.
8,345-5,380=2,965
He still needs to make 2,965 dollars. But he only makes 534 dollars a month. So you must divide 534 from 2,965 to determine how long it would take him to pay the rest of the car off.
2,965/534=5.5524344569
You get a decimal. Because he will only get his salary at the end of the month you round up regardless. So your answer will be 6 months. (Unless your teacher finds that 5.5 is a sufficient answer.)
Good luck!