There is no difference, 6rs-(-2rs) if you get rid of the parenthesis you are left with 6rs- -2rs and two negatives make a positive therefore the answer will become 8rs... I hope this helps :)
1 hr = 10/10
1/10 of an hr= 6 min
(7)(6)=42
Saturday she rode her bike for 42 min
Sunday
1 hr = 5/5
1/5 of an hr = 12 min
(3)(12)= 36
On sunday she rode her bike for 36 min
Finally
42-36= 6
She rode her bike 6 min longer on saturday than sunday
B is the answer to your question
Midpiont=(_2+3\2), (4+_1/2)
=2/2,6/2
=1,3
