Madumita is asked by her cousin to deliver a box containing 20 chocolates to her friend. Madumita is promised a reward of 10₨ for every chocolate she delivers but also a fine of 15₨ for every chocolate that she eats on her way. If she eats 5 chocolates on her way and delvers the rest, how much money will she receive from her cousin?

This can be solved by turning the information in the prompt into two equations, 20 = E + D, and (10 x D) - (15 x E) = M. For this, E represents the number of chocolates Madumita ate along the way, D represents the number of chocolates she successfully delivered, and M represents how much money she will receive from her cousin: what we are looking for. Since they give us the number she ate along the way (E), we can plug that in to the first equation to find D. ( 20 = 5 + D ----> 15 = D ) Now that we have E and D, we can plug them into the second equation to find M. (10 x 15) - (15 x 5) = M -----> 150 - 75 = 75Rs.