Answer
$45$
Work Step by Step
The order of operations follow the following hierarchy (PEMDAS rule):
(i) Parentheses/grouping symbols
(ii) Exponents
(iii) Multiplication/Division, whichever comes first from the left
(iv) Addition/Subtraction, whichever comes first from the left
Use the rule above to obtain:
$=64-16\div 4 \cdot 4 - 3
\\=64 - 4 \cdot 4 - 3
\\=64 - 16 - 3
\\=48-3
\\=45$
