13-(6,6- 2 8/15) * 3
50-(3 3/4 + 6,5):0,25

13-(66/10-38/15)*3=13-(198/30-76/30)*3=13-(122/30)*3=13-(61/15)*3=13-12.2=0.8
50-(15/4+6.5)/0.25=50-(3.75+6.5)/0.25=50-10.25/0.25=50-41=9