Răspuns :
6x(12+53)=6x65=390 6x12+6x53=72+318=390 (40+39+7)x2=86x2=172 40x2+39x2+7x2=80+78+14=172 10x(84-48)= 10x36=360 10x84-10x48=840-480=360 (100-66+17)x9=51x9=459 (100x9)-(66x9)+(17x9)=900-594+153=459