Let monthly salary of Pia = Rs.500x => Monthly salary of Som = Rs.400x Amount given by Pia to her mother = 3/5 * 500x = 300x Amount for her sister tuition fees = 15*500x/100 = 75x Amount for loan = 18*500x/100 = 90x => Amount left = 500x −(300x +75x +90x) = 2100 => 500x - 465x = 35x = 2100 => x = 2100/35 = 60 Therefore, Som's salary = 400 x 60 = Rs. 24,000