解方程： 78×3x=3.6 x÷1.98=0.4 （4.5-x）×0.375=0.75 1/2x+2/3x=14 x-0.52x=3.2×0.15 1/2x+25%=10．

答

①78×3x=3.6
       234x=3.6
  234x÷234=3.6÷234
          x=

2

145

    ②x÷1.98=0.4
x×1.98÷1.98=0.4×1.98
            x=0.792
     ③（4.5-x）×0.375=0.75
（4.5-x）×0.375÷0.375=0.75÷0.375
                 4.5-x=2
               4.5-x+x=2+x
                 2+x-2=4.5-2
                     x=2.5
④

1

2

x+

2

3

x=14
    

7

6

x=14
  

7

6

x×

6

7

=14×

6

7

       x=12
  ⑤x-0.52x=3.2×0.15
      0.48x=0.48
0.48x÷0.48=0.48÷0.48
          x=1
     ⑥

1

2

x+25%=10
     0.5x+0.25=10
0.5x+0.25-0.25=10-0.25
          0.5x=9.75
       0.5x×2=9.75×2
             x=19.5