I have word problems using d=r*t. I need help with putting the numbers and variables in the right spots to make an equation. After I figure out how to set up the equation, then I am able to solve the equation.
I need help setting up the equation.
Here is the story problem.
A person can drive from town A to town B at a certain rate of speed in 5 hours. If he increases his speed by 15kph, he can make the trip in 4 hours. How far is it from town A to town B? I made a table below but I'm not sure if everything is in the right spots.
We are dealing with the two trips, (not "the two towns").
One trip is at a slower speed and the other is at a faster speed.
Here is the chart you want to make:
Time * Speed = Distance
At slower speed
At faster speed
>>...A person can drive from town A to town B at a certain rate of speed in 5 hours...<<
We let the first (slower) speed be S
We let the distance be D
We are given that the time is 5 hours, so we fill in the first line:
Time * Speed = Distance
At slower speed 5 S D
At faster speed
>>...If he increases his speed by 15kph, he can make the trip in 4 hours...<<
To get the faster speed we add 15 kph to S, and that is S+15
The distance is the same, so it is still D
We are given that the time is 4, so we fill in the second line:
Time * Speed = Distance
At slower speed 5 S D
At faster speed 4 S+15 = D
That gives us two equations in D and S:
5S = D
4(S+15) = D
Since both equal to D, they are equal to each other:
5S = 4(S+15)
5S = 4S + 60
S = 60
So his slower speed is 60 kph (and his faster speed is 15kph faster or 75kph)
To find the distance we substitute 60 for S in 5S = D
5S = D
5(60) = D
300 = D
Therefore the distance is 300 kilometers.
Edwin