А) 12,4*14,3-12,4*4,3
в столбик!
12.4*14.3-12.4*4.3=12.4*(14.3-4.3)=12.4*10=124
12.4 × 14.3 - 12.4 × 4.3 = 12.4 × (14.3-4.3) = 12.4× 10 = 124