1.5.1÷4+4.9×25%
=5.1×0.25+4.9×0.25
=0.25（5.1+4.9）
=0.25×10
=2.5
2.2又5/1×0.75+2.2×4/1
=2.2×0.75+2.2×0.25
=2.2×（0.75+0.25）
=2.2