Math
posted by Ardine on .
Hello, I need help with a 5th grade math question. The red train returns to central station every 45 min. The blue train returns to central station every 60 min. If both trains leave the station together, in how many min. will they both be back at the station at the same time?

Assume that both trains are at the stations now, then they will be back again at the following times
red train: 45 90 135 180 225 270 315 .. minutes from now
blue train: 60 120 180 240 300 360 ... minutes from now
What do you think? 
the answer is so easy and what grade are you in

360

380