A box weighing 30 kilograms contains several student math books and one teachers edition. if each student book weighs 2.3 kilograms, the box weighs 0.4 kilograms when empty , how many student books are in the box

What are the equivalent ratios for 24/2= /3= /5.5=108/ = /15

Atorch and a battery cost 2.50 altogether.the torch costs 1.50 more than the battery.what fraction of the total price is the torch? give your answer in its simplest form.

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?