Question

alexis rode her bike 4.5 miles. johnny rode his bike 8.1 miles. how many more miles did johnny ride his bike?

Answer 1

Hey there!

The key word in there is Many more. Whenever you see that word, it usually means to subtract

So you would subtract 4.5 from 8.1
8.1
-4.5= 3.6

Answer 2

The answer is 3.6 all you needed to do was subtract the two.
To learn more on how to subtract decimals look it up on Khan Academy.
God bless :)