Pouvez-vous m'aider SVP TRES TRES URGENT

A=7/15-4/15 * 5/8
= 7/15 -2*2*5/5*3*4*2
= 7/15-2/12
= 7*12/15*12 -2*15/12*15
= 84/180 -30/180
=54/180
= 9*6/9*20
= 6/20
= 3*2/10*2
= 3/10

B= 3√2x√98 =3x√2x98 =3√196 =3x14=42