Matt and Chris leave their uncle's house in Phoenix at the same time, Matt drives west on 1-60 at a speed of 79 miles per hour. Chris drives east on 1-60 at a speed of 83 miles per hour. How many hours will it take them to be 64 miles apart

Two boats leave the same dock in Cairo at the same time. One heads north on the Mississippi River while the other heads south. The northbound boat travels five miles per hour. The

southbound boat goes seven miles per hour How many hours will it take them to be 66 miles apart?

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It will take them (Matt and Chris) 0.395 hours to be 64 miles apart

It will take 5.5 hours for the boats to be 66 miles apart

Step-by-step explanation:

We are to determine the time when Matt and Chris will be 64 miles apart, that is, when the total distance traveled by both of them will be 64 miles.

Let the time be t and

Let the distance covered by Matt be S₁ and the distance covered by Chris be S₂.

For Matt,

From the question, Matt drives at a speed of 79 miles per hour

From the formula

Distance = Speed × Time

S = v × t

∴ S₁ = 79×t

S₁ = 79t

For Chris,

From the question, Chris drives at a speed of 83 miles per hour

Using the same formula,

∴ S₂ = 83 × t

S₂ = 83t

To determine when they will be 64 miles apart, that is when S₁ + S₂ = 64 miles.

Hence,

S₁ + S₂ = 79t + 83t

∴64 = 79t + 83t

64 = 162t

t = 64/162

t = 0.395 hours

Hence, it will take them 0.395 hours to be 64 miles apart.

For the boats,

To determine how many hours it will take them to be 66 miles apart, that is when the total distance traveled by the two boats will be 66 miles.

Let the time be t and

Let the distance traveled by the northbound boat be S₁ and the distance traveled by the southbound both be S₂.

From the question,

The northbound boat travels five miles per hour

From the formula

Velocity = Distance / Time

Then, Distance = Velocity × Time

That is, S = v × t

Hence, for the northbound boat,

S = S₁

v = 5 miles per hour

∴ S₁ = 5t

Also from the question,

The  southbound boat goes seven miles per hour

Hence, for the southbound boat

S = S₂

v = 7 miles per hour

∴ S₂ = 7t

To determine when the boats will be 66 miles apart, that is when S₁ + S₂ = 66 miles

Then,

S₁ + S₂ = 5t + 7t

Hence,

66 = 5t + 7t

66 = 12t

t = 66/12

t = 5.5 hours

Hence, it will take 5.5 hours for the boats to be 66 miles apart.

if you was gonna solve for a, a is a   < -12

y= 2x+7

changed to y= 5x +7

as slope is increased from 2 to 5

therefore it would be less steeper

so, option d) is correct