So one two m one, V one squared is equal to one two M two V two squared. So let's cancel out the twos by multiplying each side by two. And then let's bring our V two over and our m one over this way. So we want velocities on the left side and masses on the right side. We get the following formula v one squared divided by V two squared equals m two squared over m one squared. And finally, let's take the square root of both sides.