Step-by-step explanation:
It's 6r+5y. But it's not in the option
Yes, is subtraction, to get their "difference".
first off, let's convert the mixed fractions, to "improper", and then subtract.

The equation that models the sequence is: 6+6 each time.
Lynne ran farther and by 7/8 miles
You can tell Lynne ran further because she ran 3 whole miles while shelly only ran 2 whole miles. Now you have to subtract to see how much Lynne had ran more.
You found a common denominator between 8 and 4. 4 can turn into 8. so you multiply 4x2 and 1x2 to get a mixed number of 2 2/8
Now you have to turn 3 1/8 because you cannot subtract 2/8 from 1/8. You can turn the fraction into 2 9/8 because there are 8 pieces in a whole.
2 9/8 - 2 2/8 = 0 7/8
Hope this helps! :)