Khalil placed 3 books he is reading in a stack. The books are 1.23 centimeters, 0.724 centimeters, and 2.1 centimeters thick. How many millimeters thick was the stack? Note: 1 centimeter = 10 millimeters

The price of a box of 15 cloud markers is $12.70. the price of a box of 42 cloud markers is $31.60. all prices are without tax, and the price of the packaging is the same for any size. how much would 50 cloud markers in a box cost? write an equation which will tell the price p for the number n markers in the box.