To simplify the expression:

2b/a + 1 - 5b/3(a+1)

First, find a common denominator for the fractions on the right side: 3(a+1)

Rewrite the expression with the common denominator:
(2b*3 - 5b)/3(a+1) + 1

Expanding the numerator in the first fraction:
(6b - 5b)/3(a+1) + 1
(b)/3(a+1) + 1
(b/3(a+1)) + 1

Therefore, the simplified expression is (b/3(a+1)) + 1.

Next, for the expression:

3a/4(b-1) - 8a/(b-1)

First, find a common denominator for the fractions on the right side: 4(b-1)

Rewrite the expression with the common denominator:
(3a*4 - 8a)/4(b-1)

Expanding the numerator in the fraction:
(12a - 8a)/4(b-1)
(4a)/4(b-1)

Simplify by canceling out the common factor of 4 in the numerator and denominator:
a/(b-1)

Therefore, the simplified expression is a/(b-1).