Carmen and gabriella each live 2 miles from the ice rink. carmen ran to the rink at a rate of 4.2 miles per hour. gabriella ran to the rink in 0.4 hours. they left their homes at the same time. who arrived at the ice rink first? (can i have an explanation of this? )

The first step to solving this is figuring out how long each girl took. From there, we can obviously see who took longer!

Let's start with Gabriella, as it's a bit easier to find how long she took.
The problem says that she ran to the rink in 0.4 hours.
Now, what is 0.4 hours in minutes? The easiest way to find that is to:
multiply 60 minutes by 0.4, since 60 minutes is one hour, and we need to find how many of those minutes is in 0.4 hours!