a) (2x-4):2<\ 2
2x+4<\ 2×2
2x+4<\ 4
2x<\ 4-4
2x<\ 0
x<\ 0
x aparţine (-infinit, 0]
b) {5×[3×(2x-8)-8]-8}=12
5×[3×(2x-8)-8]-8=12
5×[3×(2x-8)-8]=20
3×(2x-8)-8=5
3×(2x-8)=13
2x-8=13/3
2x=13/3+8 amplifici pe 8 cu 13
2x=13/3+104/13
2x=117/3
x=117/3×1/2
x=117/6