To solve this expression, we need to first add the two mixed numbers:

3 1/5 + 2 1/4

Convert 3 1/5 to an improper fraction:

3 * 5 + 1 = 15 + 1 = 16
16/5

Convert 2 1/4 to an improper fraction:

2 * 4 + 1 = 8 + 1 = 9
9/4

Now add the two improper fractions:

16/5 + 9/4

To add these fractions, we need to find a common denominator, which in this case is 20:

16/5 4/4 = 64/20
9/4 5/5 = 45/20

Now, add the two fractions:

64/20 + 45/20 = 109/20

Convert the sum back to a mixed number:

109 ÷ 20 is 5 with a remainder of 9
5 9/20

Now multiply this result by 5:

5 9/20 x 5 = 25 + 1 7/20 = 26 7/20

Finally, subtract 25 5/6:

26 7/20 - 25 5/6

Convert both mixed numbers to improper fractions:

26 * 20 + 7 = 520 + 7 = 527
527/20

25 * 6 + 5 = 150 + 5 = 155
155/6

Now find a common denominator, which is 20 * 6 = 120:

527/20 6/6 = 3162/120
155/6 20/20 = 3100/120

Subtract the two fractions:

3162/120 - 3100/120 = 62/120

Simplify the fraction:

62/120 = 31/60

Convert back to a mixed number:

31 ÷ 60 is 0 with a remainder of 31
0 31/60

So, the final result of the expression is 0 31/60.