Question 77710
I can't help you with the second one but the first one's answer is as follows.

You write down all the fractions equivalent to 5/7 ; 10/14 , 15/21 , 20/28 etc.

15/ 21 is equivalent with 5/7  Now subtract 6 from both the numerator and denominator ( because you add six but i'm working backwards) you get 12/18.

18 is six more then 12. Ther's your answer. The fraction started out at 12/18 or 2/3