48乘12.5乘0.25乘9怎么简算?(x+5)乘4=6乘（x-5)怎么解方程急着明天交作业谢谢

第一题：(8*12.5)*(4*0.25)*9=100*1*9=900
第二题：4x+20=6x-30，所以50=2x，所以x=25

48x12.5x0.25x9
=6x8x12.5x0.25x9
=6x100x0.25x9
=6x25x9
=3x2x25x9
=3x50x9
=150x9
=1350
(x+5)乘4=6乘（x-5)
4x+20=6x-30
6x-4x=20+30
2x=50
x=25