S'il Vous plait ses URGENT URGENT besoin aide a tout pris svp

5/7 × 2/3 = 10/21
13/7 - 10/21 = 39/21- 10/21
39/21-10/21 = 29/21

A= 13/7 - 5/7 * 2/3 =13/7 - 5*2 / 7*3 = 13/7 - 10/21 = 39/21 - 10/21 = (39 - 10 ) / 21 =29/21 .
B= 5/4 * ( 7/15 + 6/5 ) = 5/4 * ( 7/15 + 18/15) = 5/4 * (7+18 / 15 ) = 5/4 * 25/15 = (5*5*5) / (4*5*3) = 25/12 .