There is already a population of 1800, so then you add 3190 and 1800 to get 4900. The reason you add these numbers is because the population grows by 638 every year. They want to know how much it will grow in 5 years. You you multiply n (number) by y (year) to get t ( total).
Given that y varies inversely as x then: y=k/x where k is the constant of proportionality given by: k=yk but y=27 when x=2 thus k=27×2=54 hence the function will be: y=54x The value of x when y is 9 will be: 9=54x thus x=9/54 x=1/6
