The book shop of a particular school has 10 dozen Chemistry books, 8 dozen Physics books, 10 dozen Economics books. The selling prices are Rs 80, Rs 60 and Rs 40 each respectively. Find rhe total amount the book-shop will receive from selling all the books, using matrix algebra.

Rashid spent Rs.35.75 for Maths book and Rs.32.60 for science book.Find the total amount spent by Rashid.

Selling price of book, if 10% profit is made on purchase of book costing Rs.100 is Rs. 110.

The principal sanctioned a certain amount of money to the librarian to purchase some mathematics books costing Rs90 each . She could buy 80 books . Then she approached to a publisher who offered her a 20% discount . Find the number of copies of mathematics books which she could buy from the publisher for the sanctioned money.

In a development plan of a city, a contractor has taken a contract to construct certain houses for which he needs building materials like stones, sand etc. There are three firms A, B, C that can supply him these materials. At one time these firms A, B, C supplied him 40, 35 and 25 truck loads of stones and 10, 5 and 8 truck load of sand respectively. If the cost of one truckload of stone and sand are Rs 1200 and 500 respectively, then find the total amount paid by the contractor to each of these firms A, B, C separately.