An airplane flies 1980 km in 2.75 hours. What is its average speed in
kilometers per hour?

D)can be increased in a closed system

Adozen is 12, and your needing to calculate the weight of one medium egg, so i would do 21/12=1.75 per egg, and check your answer by doing 1.75 * 12= 21 : ) : ): ): ): ) i hoped i

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Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.