Ali buys a glass, a pencil box and a cup and pays Rs.21 to the shopkeeper. Rakesh buys a cup, two pencil boxes and a glass and pays Rs.28 to the shopkeeper. Preeti buys two glasses, a cup and two pencil boxes and pays Rs.35 to the shopkeeper. The cost of 10 cups will be

• A. Rs.40
• B. Rs.60
• C. Rs.80
• D. Rs.70