有几道不会的数学题（简便计算）7.7÷2.21.24×0.4÷1.24×0.41.2÷0.25＋1.3×49.14×1.25-1.14÷0.8

7.7÷2.2 =3.5
1.24×0.4÷1.24×0.4 =1
1.2÷0.25＋1.3×4 =10
9.14×1.25-1.14÷0.8
=10

7.7÷2.2=(7×1.1)/(2×1.1)=7/2
1.24×0.4÷1.24×0.4=1
1.2÷0.25＋1.3×4=1.2÷(1/4)＋1.3×4=1.2×4+1.3×4=2.5×4=10
9.14×1.25-1.14÷0.8=9.14×1.25-1.14×1.25=8×1.25=10