Please help with math

Write and solve a real word problem that involves determining distance on a coordinate plane

Mrs. blake's bill at a restaurant is $42.75. she wants to leave the waiter an 18% tip. how much will she pay in all, including the tip?

The half-life of a certain material is 0.002 second. approximately how much of a 14-gram sample will be left after 0.004 second? a. 12 grams b. 3.5 grams c. 0.06 gram d. 7 grams