exercice de math aidé moi svp

a)
3a+(-5+a) = 4a-5
b)
5-(-2x+3) = 5+2x-3 = 2x+2
c)
b-3-(4b+5) = b-3-4b-5 = -3b-8
d
3-y+(6-5y) = 3-y+6-5y = -6y+9