Maths questions:

Can you find out the mistakes of these steps????
1.)A/3=9+8(A-3/4)
A/3=17(A-3/4)
12*A/3=(17A-51/4)*12
4A=204A-153
A4-204A=-153
-200A/-200=-153/-200
A=153/200

2.)1-2[3-(X/2-1)]=X/4+1
-1(3-X/2-1)=X/4+1
4*(31+X/2-1)=(X/4+1)*4
-12+2X-4=X+4
2X-X=12+4+4
X=20
This answer of this sum in my book is 10 and2/3..
but i believe　This answer 　is　also　correct....