Х*10=45 000 100*х=45 000
х=45 000:10 х=45 000:100
х=4 500 х=450
.................................................................
х:100=4 000 4 000:х=100
х=4 000*100 х=40
х=400 000
.................................................................
х+190=400 х-190=400
х=400-190 х=400+190
х=210 х=590