Calculeaza in doua moduri:2x(98+345),4x(86+52),3x(157+472),6×(76+98),7×(42+783).

Răspuns :

primul mod
2×(98+345)=2×443=886
4×(86+52)=4×138=552
3×(157+472)=3×629=1887
6×(76+98)=6×174=1044
7×(42+783)=7×825=5775