80一19.4一8.09一3.51用简便方法怎么算把整个式子告诉我

问题描述:

80一19.4一8.09一3.51用简便方法怎么算把整个式子告诉我

80-19.4-8.09-3.51
=80-(19.4+8.09+3.51)
=80-31
=49