八十四又十九分之四乘以一点三七五加一百零五分又十九分之五乘以零点九
=(80+80/19)x11/8+(100+100/19)x9/10
=80x11/8+80/19x11/8+100x9/10+100/19x9/10
=110+110/19+90+90/19
=200+200/19
=210又 10/19