Answer
$-64$
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:
$=-3(2)^3-5(2)^3
\\=-3(8)-5(8)
\\=-24-40
\\=-64$
