Найдите неизвестный член пропорции x*3/20=0,39: 1,3. 3,7: 11,1=x: 7/9. 12 1/3: x=14 4/5: 0,2

3x * 1,3=20*0,39
3,9x=7,8
x=2

x*3/20=0,39:1,3               3,7:11,1=x:7/9                12 1/3:x=14 4/5:0,2 
1.3 * x = 0.39 * 3/20        11.1 * x = 3.7 * 7/9          14.8 * x = 37/3 * 0.2
1.3 * x =  0.39 * 0.15       x = (3.7 * 7/9) / 11.1        x = (37/3 * 0.2) / 14.8 
x = (0.39 * 0.15 ) / 1.3     x = 7/27                           x = 37/15 / 148/10
x = 0.045                                                                 x = 1/6