Since the multiplication is commutative and associative, you can group the factors of multiplication (the numbers) as you wish, but you need to consider the following rules:

- the multiplication of two positive factors gives a positive result

- the multiplication of two negative factors gives a positive result

- the multiplication of bne negative factor and one positive factor gives a negative result

Since there exists two negative factors and three positive factors, the result will be positive.

Group the terms in this way, such that:

`[(+1)(+3)(+5)]*[(-2)(-4)] = 15*8 = 120`

Hence, evaluating the result of the given multiplication, yields `[(+1)(+3)(+5)]*[(-2)(-4)] = 120` .