The speed of the wind is changing according to the function V(t) = - +30, where t = time in minutes after 6:00p. m. an V(20) - V(10) = -5 ?
In a period of 5 minutes, the wind speed increased from 10 mph to 20 mph.
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The wind speed decreased by 5 mph between 6:10 p. m. and 6:20 p. m.
The wind speed increased by 5 mph between 6:10 p. m. and 6:20 p. m.
In a period of 5 minutes, the wind speed decreased from 20 mph to 10 mph.