lending

A lending library has a fixed charge for the first three days and an additional charge for each day thereafter. saritha paid 27 for a book kept for seven days, while susy paid 21 for the book she kept for five days. find the fixed charge and the charge for each extra day.

A lending library has a fixed charge for the first three days and an additional charge for each day thereafter. Aarushi paid Rs 27 for a book kept for seven days. If fixed charges are Rs x and per day charges are Rs y. Write the linear equation representing the above information.