Pls ans it experts

Question

Pls answer my 2 question

Answer 1

let P of 1st campaign be : 4/10

let P of 2nd campaign be: 1/5

let P of 3rd campaign be: x

4/10 + 1/5 + x = 1

x = 4/10 = 2/5

therefore, P of 3rd campaign is 2/5

Also given that if the number of persons in second campaign was 20, so

20/(Total number of person involved) = 1/5

Total number of person involved = 20 x 5 = 100

Therefore, Total number of person involved in three campaigns is 100.