Marissa rode her bike to the park and came back home she lives 2 3/10 from the park how many miles did marissa ride her bike in all

The answer to that problem is 2*3/10 which equals 6/10, you never change or multiply or add or subtract, or divide the bottom number

Well if she went to her home and came back, that would mean Marissa rode 2 rounds. 
There are 3 ways you can do it. ( U can use the one that is the easiest)
-If each round is 2 3/10, then your gonna have to multiply it by 2.  2 3/10*2 = 4.6
-Or if you want, you can add 2 3/10 + 2 3/10 = 4.6
-Or you can convert 2 3/10 to a decimal. Then multiply it.
3/10= 0.3 
So 0.3 + 2 = 2.3 
Multiply it by 2 
= 4.6
If you wanna, you can convert it back to a fraction. 
4 6/10 ~ simplify it
=4 3/5