They only built one type, the A7V.

The answer is: Germany used 20 of her own Tanks, the A7V, and also about 50 captured British Mk IV.

Negative. The British introduced the first tank, and it was during WWI. The Germans built only one type of tank in WWI and they only built 21 of them...the A7V; it was built in 1917 and looked like a crawling shoe box.

The British Mark V, Mark IV, Renault FT, Renault FT (American), Mark I, The A7V, The Beutepanzerwagen, The Saint-Chamond, Mark IX, Mark VII Liberty Tank, The Schneider CA1, The Whippet, The LK II, The Medium Mark C, and the Ford 3-ton M1918,

MK1's and Renaults.

_________________________

Rather more than that.

The following were used in action. By 1918, many more were on the drawing-board.

Britain: MkI, MkII, MkIII, MkIV, MkV, MkV*, Medium MkA (Whippet). Plus Gun Carrier MkI (an artillery and supplies carrier)

France: Schneider, Saint-Chamond, Renault FT.

Germany: A7V + captured British MkIVs.

USA also used loaned French and British Tanks in 1918.

_________________________________

Determining the actual age is very difficult, if not impossible.

However, we do know that Altair has a spectral type of A7V so we know it is still on the main sequence.

We also know it's mass and luminosity so it is possible to deduce the length of time the star will live for: 1.6 billion years.

As the star is relatively close to us, it is possible it was created around the same time as our Sun, so it could be about half way through it's life.

So, at a guess, Altair is 800 million years old.