①498+9870÷35②420.5-294÷2.8×2.1③(2/3-2/5)÷(1/8+5/12)④2/3÷(3/4+1/12×4/5)

问题描述:

①498+9870÷35
②420.5-294÷2.8×2.1
③(2/3-2/5)÷(1/8+5/12)
④2/3÷(3/4+1/12×4/5)

答案分别是
1、780
2、 200
3、 16/39
4、40/49

①498+9870÷35=498+9870÷7÷5=498+1410÷5=498+282=780②420.5-294÷2.8×2.1=420.5-294÷4×(2.1÷0.7)=420.5-73.5×3=420.5-220.5=200③(2/3-2/5)÷(1/8+5/12)=4/15÷13/24=32/65④2/3÷(3/4+1/12×4/5)...