-2 x 5 x - 4
We must use the order of operations (Parentheses - exponents - multiplication/division - addition/subtraction)
Since this whole expression is multiplication, we will calculate it left to right.
-2 x 5 = -10 (because a negative times positive is a negative)
-10 x -4 = 40 (because a negative times a negative is a positive)
So, the final answer is 40.