A lending library has a fixed charge for the first 7 days and an additional charge for each day thereafter. Sahil paid Rs . 215 for a book kept for 15 days while Ravi paid Rs . 305 for the book he kept for 21 days. Find the fixed charge?

Solution

Let the fixed charge for first 7 days be Rs x and  Additional charge per day = Rs y As per question Sahil paid = Rs 215 for 15 days = First 7 days charge + additional charge per day × total days = x + 8 y = 215…………(i) Ravi paid Rs 305 for Rs 21 days = x + 14 y = 305…………(ii)  By solving (i) and (ii), we get  y = 15  So, the additional charge per day = Rs 15 By putting the value of y in (i), we get x + 8 y = 215 x + 8 × 15 = 215 x = 215 – 120 = Rs 95 Fixed charge for first 7 days in Rs 95.