Jason put 27 pictures on six pages of his album. Each page holds 3 large, 4 medium or 6 small pictures. He had some pictures of each size. How many pictures of each size did he have?
Let x be the number of large pictures Jason had.
He had x + 4x = <<x+4*x=5x>>5x medium pictures.
He had x + 4x + 6(6 x's) = 27 pictures in total.
x + 5x + 36x = 27
42x = 27
x = <<27/42=0.6429>>0.6429
He had 0.6429 * 3 = <<0.6429*3=1.9287>>1.9287 large pictures rounded to 2.
He had 5 * 0.6429 = <<5*0.6429=3.2145>>3.2145 medium pictures rounded to 3.
He had 6 * 0.6429 = <<6*0.6429=3.8574>>3.8574 small pictures rounded to 4.
Therefore, Jason had 2 large pictures, 3 medium pictures, and 4 small pictures. Answer: \boxed{2, 3, 4}.