In 1977, a scientific calculator cost $175. In 2004, the price was $15. Assuming that the change in price was linear, what was the approximate price of a scientific calculator in 1998?

Astick 2 m long is placed vertically at point b. the top of the stick is in line with the top of a tree as seen from point a, which is 3 m from the stick and 30 m from the tree. how tall is the tree?

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?

Two airplanes start at the same place and travel in opposite directions, one at 395 miles per hour and the other at 422 miles per hour. how many hours will it take for the planes to be 2451 miles apart?