An example on how to solve age problems in consecutive integers

What is the length of the missing leg in this right triangle? 18 mm 24 mm 26 mm 32 mm

In 2009, there were 1570 bears in a wildlife refuge. in 2010, the population had increased to approximately 1884 bears. if this trend continues and the bear population is increasing exponentially, how many bears will there be in 2018?

What percent of 18 is 24? and plz explain thx.