Answer:
Step-by-step explanation:
b/c we can substructure 5cd and 3dc b/c it doesn't matter if the place of cd and dc change. what I mean if 5 ×3=15 and it is the same with 3×5=15 both of the product are the same but, if it is - and ÷ it wil be wrong for example 5-3=2 but 3-5= -2
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