Let,the total days needed by Tanvir be M1+E1,where M1 denotes the total number of mornings and E1 denotes the total number of evenings.Now,without rain,M1+E1=29.........(1),again with rain,M1+E1=11.........(2);By adding (1) and (2)..we get M1+E1=20;therefore,the total number of days to climb the mou...