解方程 (1)x﹣x=; (2)x÷=15×; (3)40%x﹣=.
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