A certain forest covers an area of

3400 km2. Suppose that each year this area decreases by 7%. What will the area be after 15 years?

3400 (0.93) ^t

3400 (0.93) ^15 = 1144.782931 km2

The general equation for the area of the forest after t years is

A (t) = 4300 * (.93) ^t

.93 since 7 percent decrease means 93 percent stays behind. Now plug in t=12

A (12) = 4300 (.93) ^12=1799.964

So about 1800Km^2 will be left after 12 years.