Determine height of tree to nearest foot

At a sale this week, a desk is being sold for $213. this is a 29% discount from the original price. what is the original price?

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

Bob paid $3 less than tim at a local pizza parlor. together they spent $7.80. how much did bob pay for pizza?