aflati valoarea necunescutelor din :
a) 1x2-[10+7-(a:7:4)+5x2]:8=0
b) [(38xb+120):(275-250)]x54=2x2x2x3x3x3x5
c) 235-{16x100:[36-42:c:(15:3-4:1)-20]+14x5}=5
d) 105-30:{54-45:[30-24:(d-15)-7]x15+15:15}=102
                             ajutor !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!