A , P and X can complete the whole work in 22 days . A starts the work and works for “ n ” days and left while P and X complete the remaining (\frac{7}{11})th of the work in 28 days , then find the value of n ?

Let total work = 1 unit. A+P+X's combined rate = 1/22 per day. P+X complete 7/11 work in 28 days, so their rate = 7/(11×28) = 1/44 per day. Therefore A's rate = 1/22 - 1/44 = 1/44 per day. A worked for n days, completing n/44 work. The remaining 7/11 work was done by P+X. So n/44 + 7/11 = 1, giving n/44 = 4/11, hence n = 16 days.