1. write the equation y=180(0.987)^x in form of y=b+mx
2. An abandoned building's value is250(0.97)^t thousand dollars. When will Etienne be able to buy the building with his savings account, which has$180,000at t=0 and is growing by 13% each year round to 3 decimals
3. Find how much time it takes until a rain forest whose area is reduced by 50% every 13 years reaches one eighth of its starting area
4. Iodine has a half life of 8 days. if 4mg are stored for a week how much is left? how many days before only 1mg remains?