To simplify the expression 1,35:2,7+2,7:1,35+(0,4:2 1/2)x(4,2-1 3/40), we need to follow the order of operations (PEMDAS/BODMAS).

First, let's simplify the division and multiplication within parentheses:

0,4:2 1/2 = 0,4 ÷ 2 1/2
To divide a mixed number by a mixed number, we need to convert them into improper fractions:
0,4 = 4/10
2 1/2 = 5/2

0,4 ÷ 2 1/2 = (4/10) ÷ (5/2)
To divide fractions, we multiply the first fraction by the reciprocal of the second fraction:
(4/10) ÷ (5/2) = (4/10) x (2/5)
Cancel out common factors:
(4/10) x (2/5) = (2/5) x (2/5) = 4/25

Next, let's simplify the subtraction within parentheses:

4,2 - 1 3/40 = 4,2 - 43/40
To subtract a mixed number from a mixed number, we need to convert them into improper fractions:
4,2 = 42/10
1 3/40 = 43/40

42/10 - 43/40 = (42/10) - (43/40)
To subtract fractions, we need a common denominator:
(42/10) - (43/40) = (168/40) - (43/40) = (168 - 43)/40 = 125/40

Now, let's simplify the addition and subtraction:

1,35:2,7 + 2,7:1,35 + (0,4:2 1/2) x (4,2-1 3/40)
= 1,35 ÷ 2,7 + 2,7 ÷ 1,35 + (4/25) x (125/40)
= 1,35 ÷ 2,7 + 2,7 ÷ 1,35 + (4/25) x (125/40)
= (135/100) ÷ (270/100) + (270/100) ÷ (135/100) + (4/25) x (125/40)
= (135/100) x (100/270) + (270/100) x (100/135) + (4/25) x (125/40)
= (135/270) + (270/135) + (4/25) x (125/40)
= 1/2 + 2 + (4/25) x (125/40)
= 1/2 + 2 + (4/25) x (5/8)
= 1/2 + 2 + (20/200)
= 1/2 + 2 + 1/10
= 5/10 + 20/10 + 1/10
= 26/10
= 13/5

Therefore, the simplified expression is 13/5.