求未知数x.(1)x﹣25%x="1.8" (2)x:50=1.5:75 (3)x+6×4=46
5x-12.5=23×(2x+7)=45 5.6-4x=3.2
(13×0.58-4.87+0.42×13- 5.13) ×4.25
999×778+333×666
-(+)
0.5×1.6+0.5×26.4