Let Rs. x be monthly fixed charge of hostel & Rs.y be the cost of food per day
For student A, x + 20 y = 1300---(1)
For student B, x + 25y = 1500----(2)
Substract (1) from (2), we get
(x + 25y) - (x + 20y) = 1500 - 1300
⇒ 5y = 200
⇒ y = 40
∴ x + 800 = 1300 (From (1))
⇒ x = 1300 - 800 = 500
Hence, hostal fixed charge is Rs. 500 and the cost of food Rs. 40 per day