Answer
$$x=3$$
Work Step by Step
$$2^{3}-[4(5-3)^{3}]=-8x$$ Perform the operation inside the parentheses: $$(5-3) = 2$$ Substitute the value to the original equation: $$2^{3}-[4(2)^{3}]=-8x$$ To simplify the term $[4(2)^{3}]$, get the value of to raise to the 3rd power then multiply to 4. Thus,
$$[4(2)^{3}] = [4(8)] = 32$$
Rewrite the equation: $$2^{3}-32=-8x$$ $$8-32=-8x$$ $$-24=-8x$$
Divide both sides by $-8$:
$$3 = x$$ $or$ $$x = 3$$