The total cost of 8 pens and 9 books is $30.05. if the cost of a pen is $a, and a book is .90 MORE expensive. find A. Give your answer in two decimal places. !BRAINLIEST!

Carter drank 15.75 gallons of water in 4 weeks. he drank the same amount of water each day. a. estimate how many gallons he drank in one day. b. estimate how many gallons he drank in one week. c. about how many days altogether will it take him to drink 20 gallons?

You are a clerk at convenience store. a customer owes 11.69 for a bag of potatoes chips. she gives you a five dollar bill. how much change should the customer receive?

Ageologist had two rocks on a scale that weighed 4.6 kilograms together. rock a was 0.5 of the total weight. how much did rock a weigh?