3/4 x [ 12 x 4 + (- 16) ] + (-20)
a.16

b.-44

c.44

d.4

(3/4)*[12*4+(-16)]+(-20)  

PEMDAS is order of operations...

Parentheses first, exponents next, multiplication/division, finally addition/subtraction.

So the first thing you need to address is the innermost parentheses

(3/4)[12*4-16]+(-20)  now you have multiplication in one set of parentheses

(3/4)[48-16]+(-20)  now you still have addition/subtraction in the middle parentheses

(3/4)(32)+(-20)  and you have a multiplication in for the last parentheses

(3/4)(32)-20  we have multiplication on left side

96/4-20  now we have division on left

24-20  and finally subtraction

4