How to write an equation

Question

I have a graph that shows karrie rides her bicycle 20 km per every 1 hour. The question is Write an equation that relates the distance, in kilometers, Karrie rides, y, and the time, in hours, she rides, x. I understand the answer to that now it's asking Doug also starts 120 km from the ending point, but starts 1 hour after Karrie.  He rides at an average speed of 18 km per hour.  Using x-1 to represent Doug's time, because he starts 1 hr after Karrie, write an equation that can be used to determine the number of hours that it takes Doug to reach the ending point and then solve the equation you wrote to determine the amount of time it takes Doug to reach the ending point.  I'm confused with the x-1.  Would it be...

 

120=18 * x-1

 

120/18 = 6.67-1 = 5.67 hours?

Answer 1

Hailey, I'm going to assume you meant to type 120 and not 129.

 

You forgot to distribute.

 

120 = 18(x - 1)

120 = 18x - 18

138 = 18x

x = 7.67 hours