To add these two numbers, we need to first convert any mixed numbers to improper fractions.

-1 3/4 = -1 + 3/4 = -4/4 + 3/4 = -1/4
3 5/14 = 3 + 5/14 = 42/14 + 5/14 = 47/14
5,4 = 5
1,75 = 1 + 0.75 = 1 + 3/4 = 4/4 + 3/4 = 7/4
2 6/7 = 2 + 6/7 = 14/7 + 6/7 = 20/7
5,4 = 5

Now we can add these values:

(-1/4) + (47/14) + 5 + (7/4) + (20/7) + 5
= -1/4 + 47/14 + 5 + 7/4 + 20/7 + 5
= -3/28 + 47/14 + 35/7 + 20/7
= -3/28 + 94/28 + 140/28 + 80/28
= (94 + 140 + 80 - 3) / 28
= 311 / 28

Therefore, the sum of these two numbers is 311/28.