Răspuns:
3x4+3x5=3(4+5)=3x9=27
3129x22-3129x20=3129(22-21)=3129x1=3129
5+5x2+13x5+13x7=5(1+2)+13(5+7)=5x3+13x12=15+156=171
425x8+2x425=425(8+2)=425x10=4250
6x19+6=6(19+1)=6x20=120
86x5-80x5=5(86-80)=5x6=30
7x4+7x1=7(4+1)=7x5=35
4x29+4=4 (29+1)=4x30=120
3x4x23-17x3x4=3x4(23-17)=12x6=72
9x11-9x1=9(11-1)=9x10=90
43x11-43=43(11-1)=43x10=430
Explicație pas cu pas: