Solve using the elimination method.
-7x – 8y = -23 and 4x + 4y = 12

Aquantity with an initial value of 3900 decays exponentially at a rate of 35% every hour. what is the value of the quantity after 0.5 days, to the nearest hundredth?

The jewelry store is having a sale. necklaces that were regularly priced at $23.50 are on sale for $18.80. what is the percentage of decrease in the price of necklaces?

Katie wants to collect over 100 seashells. she already has 34 seashells in her collection. each day, she finds 12 more seashells on the beach. katie can use fractions of days to find seashells. write an inequality to determine the number of days, dd, it will take katie to collect over 100 seashells.