18.
. va roggggg mult !!!

Răspuns:
a.42/21+(-10/10)=2-1=1
b. -5/4+1/4=-4/4=-1
c. 16×(1×4+1)/4-1=16×5/4-1=20-1=19
d.2/15×(3×4+3)/4-3/1×5/6=2/15×15/4-3/1×5/2=1/2-5/2=-4/2= -2