slvp aidez moi le c et le d de l exercice 29 merci d avance

-4/5+y = 3/10-1/2y
y +1/2 y =4/5 +3/10
2/2y +1/2y = 8/10+3/10
3/2y = 11/10
y = 11/10*2/3 = 22/30

5/2a +1/4 = 1/4 a +2/5
5/2a -1/4a = 2/5-1/4
10/4a-1/4a = 8/20-5/20
9/4a= 3/20
a = 3/20*4/9 = 12/180 =1/15