First, let's simplify the expression (9/34-1 20/510):

9/34 = 90/340 = 45/170
1 20/510 = 1 + 20/510 = 1 + 4/51 = 51/51 + 4/51 = 55/51

Now, we can subtract these two fractions:
45/170 - 55/51 = (4551)/(17051) - (55170)/(51170)
= 2295/8670 - 9350/8670
= -7055/8670
= -395/482

Next, let's simplify the expression -2 1/5:
-2 1/5 = -2 + 1/5 = -10/5 + 1/5 = -9/5

And finally, let's add this result to 5/28:
-9/5 + 5/28 = -252/140 +25/140 = -227/140

Therefore, the final result is -227/140.