Samantha and Jillian were going for a walk. Jillian left 15 seconds ahead of Samantha. Samantha walked at a speed of 7 feet per second. Jillian walked at a speed of 6 feet per second. How many seconds had Jillian been walking when the two girls had walked the same distance?

  105 seconds

Step-by-step explanation:

We can use the relation ...

  distance = speed · time

to write equations for the distance each girl travels as a function of time t since Jillian started.

  Jillian's distance = (6 ft/s)(t)

  Samantha's distance = (7 ft/s)(t -15) . . . . Samantha starts 15 seconds after the clock starts running

These distances are the same when ...

  6t = 7(t -15)

  6t = 7t -105 . . . . eliminate parentheses

  105 = t . . . . . . . . add 105-6t

Jillian had been walking 105 seconds when the two girls met.

s

step-by-step explanation: