I think it would be about 27 bushes.
To find x, use the Pythagorean Theorem. 30^2 + 12^2 = x^2
900 + 144 = x^2
1044 = x^2
Take the square root of both sides so that x = 32 (rounded to the nearest whole number)
11 bushes can be planted on the 30 ft side
5 on the 12 ft side
In order to be able to plant a 12th bush on the x side, it would need to be 33 ft long. Since the side is only 32 ft long, only 11 bushes can be planted on that side.
Add them all together (11 + 5 + 11) to get 27. Hope this helps