Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Number | Year built | Livery | Current status | Notes |
| --- | --- | --- | --- | --- |
| 2 | 1964 | Red and white | Operational | Based on a Metropolitan Tramway style open-topper |
| 4 | 1961 | Blackpool Tramway green and cream | Operational | Based on a Blackpool style Open Boat |
| 6 | 1954 | Green and cream | Operational | Based on a Llandudno & Colwyn Bay style open-topper |
| 7 | 1958 | Brown and cream | Stored awaiting overhaul | Based on a Llandudno & Colwyn Bay style open-topper |
| 8 | 1968 | Bristol blue and white | Operational | Based on a Llandudno & Colwyn Bay style open-topper |
| 9 | 2002 | Two tone blue | Operational | Based on design elements from Plymouth and Blackburn tramcars |
| 10 | 2002 | Orange, green and cream | Operational | Based on design elements from Plymouth and Blackburn tramcars |
| 11 | 2002 | Pink | Operational | Based on design elements from Plymouth and Blackburn tramcars |
| 12 | 1966 | Currently being repainted into London Transport red and cream | Operational | Based on a London Feltham-type tram |
| 14 | 1904 | Red and white | Operational | Ex Metropolitan Tramways 94. Rebuilt into its current format in 1984 |
| 16 | 1921 | Crimson and yellow | Operational | Ex Bournemouth 106. Rebuilt into its current format in 1992 |
| 17 | 1988 | Red and white | Operational | Based on a Manx Electric Railway toastrack tram |
| 19 | 1906 | Green and white | Operational | Ex Exeter 19. Rebuilt into its current format in 1998 |
Question:
how many cars are based on the plymouth and blackburn tramcars?
Answer:
3