is this invitation to treat or an offer and if so where is the acceptance?

as a result of the financial difficulties Paul was experiencing, he decided to sell the car.

on 15^th November - he placed an advertisement in the local newspaper which stated as follows: 'Almost new Toyota car for sale, contact me on 07891556999'.

On 16^th November - Vera saw the advertisement. She called the phone number. Paul picked up and when she asked how much he would sell the car, Paul replied that it was for 5,000.Vera responded by saying that it was certainly not a new car and she would prefer to buy it for 4,000.