My trip to work is 120 miles. If I go 8 mph faster than my usual speed, I'll get to work 30 minutes earlier. How long does my trip take, in hours, if I go my usual speed?
Hi, what I have so far are the equations 120=rt and
t-30 = \(\frac{120}{r+8}\)
which equals to \(t=\frac{120}{r+8}+30\)
However, when I plug the expression for the value of t into 120=rt I've gotten answers that don't work. Could someone explain or point out what is wrong? Thanks!
You are mixing dimensions...
your rate is in mile per HOUR
your increase in time is in MINUTES.....convert 30 MINUTES to 1/2 hour and resolve for r
120/(r+8) + 1/2 = 120/r