a) $3/4+1/6$ : 3 + $5/6-1/2$ : 9
First, let's simplify the fractions:

3/4 + 1/6 = 9/12 + 2/12 = 11/12

5/6 - 1/2 = 10/12 - 6/12 = 4/12

Now we can plug these values into the equation:

$11/12$ : 3 + $4/12$ : 9
= 11/36 + 4/108
= 11/36 + 1/27
= $11<em>3$/$36</em>3$ + 1/27
= 33/108 + 1/27
= 33/108 + 4/108
= 37/108

b) $3/4-5/12$ * 3 - 1/16 : 1/8
Let's simplify the fractions first:

3/4 - 5/12 = 9/12 - 5/12 = 4/12 = 1/3

Now we can plug these values into the equation:

$1/3$ 3 - 1/16 : 1/8
= 1 - 1/16 : 1/8
= 1 - $1/16</em>8$ = 1 - 1/2
= 1/2