Mary left with a speed of 51 mph. Alyssa left in the opposite direction at the same time traveling 68 mph. How long does Alyssa need to travel before that are 315 miles apart

2.65 hours

Step-by-step explanation:

relative speed = 51 + 68 = 119

315 / 119 = 2.65 hours

Answer: it will take 2.65 hours

Step-by-step explanation:

Let t represent the time it takes for them to be 315 miles apart.

By the time both of them are 315 miles apart, then, they would have travelled a total distance of 315 miles.

Distance = speed * time

Mary left with a speed of 51 mph. This means that the distance that she would travel in t hours is 51 * t = 51t

Alyssa left in the opposite direction at the same time traveling 68 mph. This means that the distance that she would travel in t hours is 68 * t = 68t

Since the total distance is 315 miles, the.

51t + 68t = 315

119t = 315

t = 315/119

t = 2.65 hours