bonsoir
a = ( 2 + 1/5) : ( 2 - 1/5)
a = ( 10/5 + 1/5) : ( 10/5 - 1/5)
a = 11/5 : 9/5
a = 11/5 x 5/9
a = 55/45
a = 11/9
b = - 7/3 + 8/15
b = - 35/15 + 8/15
b = - 27/15
b = - 3/5
impôts + assurances = 2 860 : 4 = 715 €
restent 2 145 €
logement = 2 145 x 3/20 = 321.75 €
nourriture = 2 145 x 4/15 = 572 €
voiture = 2 145 : 5 = 429 €