Question

10a-(3a-9b)=7a+9b
(0,5c+d)-2(0,5-3c)=6,5c

Answer 1

10а-3а+9b=7a+9b
7a-7a= 9b-9b
0=0

0,5c+d-1+6c=6,5c
d-1+6,5c=6,5c
d-1=6,5c-6,5c
d-1=0
d=1