To simplify the expression, we first need to convert the mixed numbers into improper fractions:

7/8 √5 = 7/8 √5

11/49 = 11/49

1,5 √7 = 1 + 1/2 = 3/2 √7

1/9 = 1/9

Now, we can rewrite the expression as:

(7/8 √5) - (11/49) - (3/2 √7) - (1/9)

Next, we need to find a common denominator to combine the terms:

LCD = 8499 = 3528

Now we rewrite each fraction with the LCD:

(7/8 √5) = (7441/3528 √5) = 3087/3528 √5

(11/49) = (11*72/3528) = 792/3528

(3/2 √7) = (31764/3528 √7) = 5292/3528 √7

(1/9) = (1*392/3528) = 392/3528

Now our expression becomes:

(3087/3528 √5) - (792/3528) - (5292/3528 √7) - (392/3528)

Now we can combine the terms:

= (3087 √5 - 792 - 5292 √7 - 392)/3528

= (3087 √5 - 5292 √7 - 792 - 392)/3528

Therefore, the simplified expression is:

(3087 √5 - 5292 √7 - 792 - 392)/3528