Răspuns:
21×(2+3+4)=21×9=189
(31+250-12)×2=269×2=618
4×(100-20-15)=4×65=260
(50-15+22)×4=57×4=221
(3+2)×13=65
(10-2)×15=120
25×(2+4)=150
12×(10-3)=84
