Question

7s/20-2s/5+s/4+3s/20=1/10
Pra agora pff to disisperada :(

Answer 1

7s - 2s  + s  + 3s  =    1
20    5      4     20       10

7s + 3s - 2s + s =  1
20    20    5     4    10

10s - 2s + s  =  1
 20     5     4     10

s -  2 s + s  =   1
2     5      4      10

10s - 8s + 5s =   2
      20               20

10s - 8s + 5s = 2
2s + 5s = 2
7s = 2
R.: s = 2/7
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mmc (2,5,4,10) = 20

2,5,4,10: 2
1,5,2,5: 2
1,5,1,5: 5
1,1,1,1      = 2.2.5 = 4.5 = 20