39*13+35*39+46*61=39*48+46*61=39*48+48*61-61*2=4800-122=4678
968*49/98=(968/2)*(49*2)/98=968/2=484
39乘13加35乘39加46乘61 968乘49除以98
39*13+35*39+46*61=39*48+46*61=39*48+48*61-61*2=4800-122=4678
968*49/98=(968/2)*(49*2)/98=968/2=484