How do I solve?

Question

A car and truck leave a city traveling in opposite directions. The car is going 12mph slower than the truck. After 3/4 hours, the car reaches its destination. After 2 1/2 hours, the truck reaches its destination. They end up 199 miles apart. What's the speed of each vehicle?

Answer 1

The separation distance of 199 miles between the truck and car is the sum of the distances each traveled.  Compute the distances, add them, set equal to 199 miles, and solve for the speeds.

 

v = speed of truck

v - 12 = speed of car

 

Truck:

 

d₁ = vt₁ = 2.5v

 

Car:

 

d₂ = (v - 12)t₂ = 0.75(v - 12)

 

d₁ + d₂ = 199

 

2.5v + 0.75(v - 12) = 199

 

Solve for v.  That is the truck speed.  Then v - 12 is the car speed.  Can you finish from here?

Answer 2

d = r · t

t represents speed of truck

t - 12 represents speed of car

 

2.5t + (0.75)(t - 12) = 199

 

Can you solve for t and answer