`a)`

`A = (-4/3 + 5/11) : 7/12 + (-2/3 + 17/11) : 7/12`

`A = (-4/3 + 5/11 + -2/3 + 17/11) : 7/12`

`A = [(-4/3 + -2/3) + (5/11 + 17/11)] : 7/12`

`A = (-6/3 + 22/11) : 7/12`

`A = (-2 + 2) : 7/12`

`A = 0 : 7/12`

`A = 0`

`b)`

`B = 2025^0 * sqrt(16) - 2 * sqrt((-2)^2) - 8 * sqrt(9/16)`

`B = 1 * 4 - 2 * |-2| - 8 * 3/4`

`B = 4 - 2 * 2 - 6`

`B = 4 - 4 - 6`

`B = -6`

`c)`

`C = (3/7 - 3/11 + 3/17) / (5/7 - 5/11 + 5/17) + (1/2 - 1/3 + 1/4) / (5/4 - 5/6 + 5/8)`

`C = [3 * (1/7 - 1/11 + 1/17)] / [5 * (1/7 - 1/11 + 1/17)] + (1/2 - 1/3 + 1/4) / [5/2 * (1/2 - 1/3 + 1/4)]`

`C = 3/5 + 1 / (5/2)`

`C = 3/5 + 2/5`

`C = 5/5`

`C = 1`