How you simplify fractions is figuring out what the highest number that can go into them is.
I now that's a bit confusing but I'll explain.
In this case, 2 can go into both 10 and six, (because 2×5=10 and 2×3=6) and no higher number can, so the simplified version of 6/10 is 3/5. (the numbers we multiplied by 2)
